Remove bitrig #[cfgs

Bitrig is in the process of re-merging with OpenBSD as is no longer
actively developed. Additionally it was never tested, and probably
was quite broken, for nix. So let's remove all references and not
even pretend to support it.

Author: Bryant Mairs

src/errno.rs

@@ -13,16 +13,6 @@ unsafe fn errno_location() -> *mut c_int {
     __error()
 }
 
-#[cfg(target_os = "bitrig")]
-fn errno_location() -> *mut c_int {
-    extern {
-        fn __errno() -> *mut c_int;
-    }
-    unsafe {
-        __errno()
-    }
-}
-
 #[cfg(target_os = "dragonfly")]
 unsafe fn errno_location() -> *mut c_int {
     extern { fn __dfly_error() -> *mut c_int; }
@@ -520,7 +510,7 @@ fn desc(errno: Errno) -> &'static str {
 
         #[cfg(target_os = "dragonfly")]
         EUNUSED94 | EUNUSED95 | EUNUSED96 | EUNUSED97 | EUNUSED98 => "Unused",
- 
+
         #[cfg(target_os = "dragonfly")]
         EASYNC          => "Async",
     }

src/sys/aio.rs

@@ -19,8 +19,7 @@ libc_enum! {
         /// do it like `fsync`
         O_SYNC,
         /// on supported operating systems only, do it like `fdatasync`
-        #[cfg(any(target_os = "bitrig",
-                  target_os = "ios",
+        #[cfg(any(target_os = "ios",
                   target_os = "linux",
                   target_os = "macos",
                   target_os = "netbsd",