mesa: ASSERT macro is already defined by WinCE headers.

Even when just the standard headers are used....

src/mesa/main/glheader.h

@@ -233,6 +233,7 @@
 #endif
 
 
+#if !defined(_WIN32_WCE)
 #if defined(BUILD_FOR_SNAP) && defined(CHECKED)
 #  define ASSERT(X)   _CHECK(X) 
 #elif defined(DEBUG)
@@ -240,6 +241,7 @@
 #else
 #  define ASSERT(X)
 #endif
+#endif
 
 
 #if !defined __GNUC__ || __GNUC__ < 3