ARM broken, need cast

[MagaTailor]

Due to this issue, even a GL "hello world" doesn't compile:

/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/input.rs:65:64: 65:83 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/input.rs:65             if (display.xlib.XQueryExtension)(display.display, xinput_str.as_ptr(), &mut opcode, &mut event, &mut error) == ffi::False {
                                                                                                                                                                 ^~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/input.rs:65:64: 65:83 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:460:61: 460:74 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:460                 (display.xlib.XInternAtom)(display.display, delete_window, 0)
                                                                                                                                                                ^~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:460:61: 460:74 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:464:68: 464:73 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:464                 (display.xlib.XStoreName)(display.display, window, title);
                                                                                                                                                                       ^~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:464:68: 464:73 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:513:36: 513:63 error: mismatched types:
 expected `*mut i8`,
    found `*mut u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:513                 (*hint).res_name = c_name as *mut libc::c_char;
                                                                                                                                       ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:513:36: 513:63 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:514:37: 514:64 error: mismatched types:
 expected `*mut i8`,
    found `*mut u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:514                 (*hint).res_class = c_name as *mut libc::c_char;
                                                                                                                                        ^~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:514:37: 514:64 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:525:65: 525:70 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:525                     (display.xlib.XInternAtom)(display.display, state, 0)
                                                                                                                                                                    ^~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:525:65: 525:70 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:530:65: 530:81 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:530                     (display.xlib.XInternAtom)(display.display, state_fullscreen, 0)
                                                                                                                                                                    ^~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:530:65: 530:81 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:640:85: 640:90 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:640             (self.x.display.xlib.XStoreName)(self.x.display.display, self.x.window, title);
                                                                                                                                                                                        ^~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:640:85: 640:90 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:792:101: 792:118 error: mismatched types:
 expected `*const i8`,
    found `*const u8`
(expected i8,
    found u8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:792             let xcursor = (self.x.display.xcursor.XcursorLibraryLoadCursor)(self.x.display.display, c_string.as_ptr());
                                                                                                                                                                                                        ^~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:792:101: 792:118 help: run `rustc --explain E0308` to see a detailed explanation
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/platform/linux/api_dispatch.rs:402:36: 402:66 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/platform/linux/api_dispatch.rs:402         let error = CStr::from_ptr(buff.as_mut_ptr() as *const i8).to_string_lossy();
                                                                                                                                                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/home/odroid/.cargo/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/platform/linux/api_dispatch.rs:402:36: 402:66 help: run `rustc --explain E0308` to see a detailed explanation
error: aborting due to 10 previous errors
Could not compile `glutin`.

In most cases it's enough to do a cast as *const _ while the rest might require coercion via a variable.

I was using a 1.7 nightly, 1.5 is also affected but in other places too.

[MagaTailor]

Stable rust 1.5 will require two additional casts:

 Compiling glutin v1.4.5
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/glx/mod.rs:36:7: 36:21 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/glx/mod.rs:36     f(c_str.as_ptr())
                                                                                                  ^~~~~~~~~~~~~~
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/glx/mod.rs:36:7: 36:21 help: run `rustc --explain E0308` to see a detailed explanation
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:42:7: 42:21 error: mismatched types:
 expected `*const u8`,
    found `*const i8`
(expected u8,
    found i8) [E0308]
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:42     f(c_str.as_ptr())
                                                                                                     ^~~~~~~~~~~~~~
/tmp/.cargo-1.5/registry/src/github.com-48ad6e4054423464/glutin-0.4.5/src/api/x11/window.rs:42:7: 42:21 help: run `rustc --explain E0308` to see a detailed explanation

[elinorbgr]

Switching from using libc to std::os::raw for basic C types fixes this, and if lucky allow to drop the libc dependency altogether.