Auto merge of #405 - mmun:patch-1, r=alexcrichton

Add getchar_unlocked and putchar_unlocked

Adds [getchar_unlocked](http://pubs.opengroup.org/onlinepubs/9699919799/functions/getchar_unlocked.html) and [putchar_unlocked](http://pubs.opengroup.org/onlinepubs/9699919799/functions/putchar_unlocked.html).

Author: bors

src/unix/mod.rs

@@ -251,6 +251,8 @@ extern {
     pub fn fscanf(stream: *mut ::FILE, format: *const ::c_char, ...) -> ::c_int;
     pub fn scanf(format: *const ::c_char, ...) -> ::c_int;
     pub fn sscanf(s: *const ::c_char, format: *const ::c_char, ...) -> ::c_int;
+    pub fn getchar_unlocked() -> ::c_int;
+    pub fn putchar_unlocked(c: ::c_int) -> ::c_int;
 
     #[cfg_attr(target_os = "netbsd", link_name = "__socket30")]
     pub fn socket(domain: ::c_int, ty: ::c_int, protocol: ::c_int) -> ::c_int;