Fix this_platform_is_not_supported on OpenBSD.

I followed the steps of @mneumann.

src/api/caca/mod.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 #![allow(unused_variables, dead_code)]
 
 use libc;

src/api/dlopen.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 #![allow(dead_code)]
 
 use std::os::raw::{c_void, c_char, c_int};

src/api/egl/ffi.rs

@@ -33,5 +33,5 @@ pub type EGLNativeWindowType = winapi::HWND;
 pub type EGLNativeWindowType = *const libc::c_void;
 #[cfg(target_os = "android")]
 pub type EGLNativeWindowType = *const libc::c_void;
-#[cfg(any(target_os = "dragonfly", target_os = "freebsd"))]
+#[cfg(any(target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 pub type EGLNativeWindowType = *const libc::c_void;

src/api/egl/mod.rs

@@ -1,5 +1,5 @@
 #![cfg(any(target_os = "windows", target_os = "linux", target_os = "android",
-           target_os = "dragonfly", target_os = "freebsd"))]
+           target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 #![allow(unused_variables)]
 
 use ContextError;

src/api/glx/mod.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 
 use ContextError;
 use CreationError;

src/api/osmesa/mod.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 
 extern crate osmesa_sys;
 

src/api/wayland/mod.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 
 pub use self::monitor::{MonitorId, get_available_monitors, get_primary_monitor};
 pub use self::window::{PollEventsIterator, WaitEventsIterator, Window, WindowProxy};

src/api/x11/mod.rs

@@ -1,4 +1,4 @@
-#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd"))]
+#![cfg(any(target_os = "linux", target_os = "dragonfly", target_os = "freebsd", target_os = "openbsd"))]
 
 pub use self::monitor::{MonitorId, get_available_monitors, get_primary_monitor};
 pub use self::window::{Window, XWindow, PollEventsIterator, WaitEventsIterator, Context, WindowProxy};