Import change from ctype.h revision 1.20 from openbsd

Fixes builds with gcc >= 4.3 with -std=gnu99

Change-Id:	I8729b7f4237fd7a99a82b2fe60573a7afe66b435
diff --git a/libc/include/ctype.h b/libc/include/ctype.h
index b5f9ff4..58b76ea 100644
--- a/libc/include/ctype.h
+++ b/libc/include/ctype.h
@@ -59,7 +59,11 @@
 
 /* extern __inline is a GNU C extension */
 #ifdef __GNUC__
+#  if defined(__GNUC_STDC_INLINE__)
+#define	__CTYPE_INLINE	extern __inline __attribute__((__gnu_inline__))
+#  else
 #define	__CTYPE_INLINE	extern __inline
+#  endif
 #else
 #define	__CTYPE_INLINE	static __inline
 #endif