On Unix, fix cross-compiling to wasm32

Aborting compilation by using 'compile_error!' macro in build.rs was resulting in failing cross
compilation, thus this commit removes build.rs. The compilation will now be aborted on existing 'compile_error!' macros in corresponding platform sources.

CHANGELOG.md

@@ -5,6 +5,7 @@
 - On Windows, fix bug preventing windows with transparency enabled from having fully-opaque regions.
 - **Breaking:** On Windows, include prefix byte in scancodes.
 - On Wayland, fix window not being resizeable when using `with_min_inner_size` in `WindowBuilder`.
+- On Unix, fix cross-compiling to wasm32 without enabling X11 or Wayland.
 
 # 0.23.0 (2020-10-02)
 

build.rs

@@ -1,21 +0,0 @@
-#[cfg(all(
-    any(
-        target_os = "linux",
-        target_os = "dragonfly",
-        target_os = "freebsd",
-        target_os = "netbsd",
-        target_os = "openbsd"
-    ),
-    not(feature = "x11"),
-    not(feature = "wayland")
-))]
-compile_error!("at least one of the \"x11\"/\"wayland\" features must be enabled");
-
-#[cfg(all(
-    target_arch = "wasm32",
-    not(feature = "web-sys"),
-    not(feature = "stdweb")
-))]
-compile_error!("at least one of the \"web-sys\"/\"stdweb\" features must be enabled");
-
-fn main() {}