mesa: include stdio.h where needed

Instead of relying on glapi.h or some other header to provide it.

Acked-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: José Fonseca <jfonseca@vmware.com>

src/mesa/main/errors.c

@@ -29,6 +29,7 @@
 
 
 #include <stdarg.h>
+#include <stdio.h>
 #include "errors.h"
 #include "enums.h"
 #include "imports.h"