Remove bit_field type from Odin (keyword and dead runtime code still exists)

core/os/os_windows.odin

@@ -195,4 +195,4 @@ is_windows_8_1 :: proc() -> bool {
 is_windows_10 :: proc() -> bool {
 	osvi := get_windows_version_w();
 	return (osvi.dwMajorVersion == 10 && osvi.dwMinorVersion == 0);
-}
+}