Define Display as c_void instead of *mut c_void to match Xlib

Xlib defines `Display` as follows:

    typedef struct _XDisplay Display;

And then always references this type as a pointer to it, e.g. `Display
*`.  The same happens in `ash`, where `Display` is only ever referenced
as a raw pointer via `*mut Display`, so making `Display` itself a type
alias to `*mut c_void` is wrong and confusing.  Switch it back to a
`c_void` to match the forward-declared (but otherwise undefined) `struct
_XDisplay`.

Changelog.md

@@ -26,6 +26,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   - `ExternalMemoryFd::get_memory_fd_properties()`
   - `ExternalMemoryWin32::get_memory_win32_handle_properties()`
   - `GetSurfaceCapabilities2::get_physical_device_surface_capabilities2()`
+- Define `Display` as `c_void` instead of `*mut c_void` to match Xlib (#751)
 - `VK_KHR_device_group_creation`: Take borrow of `Entry` in `fn new()` (#753)
 
 ### Removed
@@ -315,7 +316,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### 0.29.0
 
-- -Breaking-: Removed Display impl for flags. The Debug impl now reports flags by name.
+- _Breaking_: Removed Display impl for flags. The Debug impl now reports flags by name.
 - Functions now have a doc comment that links to the Vulkan spec
 - Entry has a new method called `try_enumerate_instance_version` which can be used in a 1.0 context.
 - The generator now uses `BTreeMap` for better diffs.
@@ -324,9 +325,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Switched to a new [changelog](https://keepachangelog.com/en/1.0.0/) format
 - Fixed a build issue on ARM.
-- -Breaking- Arrays are now passed by reference.
+- _Breaking_: Arrays are now passed by reference.
 - Builders are now marked as `#[transparent]`.
-- -Breaking-  Renamed `.next(..)` to `push_next`. `push_next` is only available on structs that are passed directly. Additionally `push_next` only accepts structs that can be inserted into the pointer chain. Read the readme for more information.
+- _Breaking_: Renamed `.next(..)` to `push_next`. `push_next` is only available on structs that are passed directly. Additionally `push_next` only accepts structs that can be inserted into the pointer chain. Read the readme for more information.
 - New -experimental- extensions. Those do not follow the semver rules and can be removed at any time.
 - Added `AmdGpaInterface` extension.
 
@@ -391,7 +392,7 @@ flags: vk::CommandPoolCreateFlags::RESET_COMMAND_BUFFER_BIT,
 - `map_memory` now returns a void ptr
 
 - `ash::util::Align` is a helper struct that
-can write to aligned memory.
+  can write to aligned memory.
 
 [Unreleased]: https://github.com/MaikKlein/ash/compare/0.37.2...HEAD
 [0.37.2]: https://github.com/MaikKlein/ash/releases/tag/0.37.2

ash/src/extensions/khr/xlib_surface.rs

@@ -43,7 +43,7 @@ impl XlibSurface {
         &self,
         physical_device: vk::PhysicalDevice,
         queue_family_index: u32,
-        display: &mut vk::Display,
+        display: *mut vk::Display,
         visual_id: vk::VisualID,
     ) -> bool {
         let b = (self.fp.get_physical_device_xlib_presentation_support_khr)(

ash/src/vk/platform_types.rs

@@ -3,7 +3,7 @@
 use std::os::raw::*;
 pub type RROutput = c_ulong;
 pub type VisualID = c_uint;
-pub type Display = *const c_void;
+pub type Display = c_void;
 pub type Window = c_ulong;
 pub type xcb_connection_t = c_void;
 pub type xcb_window_t = u32;