Before messing with macros from stdio.h, include cstdio. Some parts of

the backend would include it afterwards and the macro changes conflict
with libc++'s version of cstdio.

external/gpl3/gcc/dist/gcc/system.h

@@ -37,6 +37,12 @@ along with GCC; see the file COPYING3.  If not see
 # include <stddef.h>
 #endif
 
+#ifndef GENERATOR_FILE
+#ifdef __cplusplus
+# include <cstdio>
+#endif
+#endif
+
 #include <stdio.h>
 
 /* Define a generic NULL if one hasn't already been defined.  */