glsl: define __STDC_FORMAT_MACROS to get PRIx64 macro

Otherwise, inttypes.h may not define the macro for C++ on MinGW.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=98681
Reviewed-by: Emil Velikov <emil.velikov@collabora.com>

src/compiler/glsl/ir_builder_print_visitor.cpp

@@ -21,6 +21,7 @@
  * DEALINGS IN THE SOFTWARE.
  */
 
+#define __STDC_FORMAT_MACROS 1
 #include <inttypes.h> /* for PRIx64 macro */
 #include "ir.h"
 #include "ir_hierarchical_visitor.h"