src/types/bool_type.h: Undefine Bool if defined

X11's use of #defines strike again.

Fixes tint -> dawn autoroller

Change-Id: Iccac4f2ac3a548b490dafc54e024a858419080e6
Reviewed-on: https://dawn-review.googlesource.com/c/tint/+/39760
Auto-Submit: Ben Clayton <bclayton@google.com>
Reviewed-by: dan sinclair <dsinclair@chromium.org>
Commit-Queue: dan sinclair <dsinclair@chromium.org>

src/type/bool_type.h

@@ -19,6 +19,12 @@
 
 #include "src/type/type.h"
 
+// X11 likes to #define Bool leading to confusing error messages.
+// If its defined, undefine it.
+#ifdef Bool
+#undef Bool
+#endif
+
 namespace tint {
 namespace type {