Declare getgrent/setgrent/endgrent as missing.

Bug: 19340053
Change-Id: I42bfeda95e6f262e2e74ab47336ea346c2de7e4a
diff --git a/libc/include/sys/cdefs.h b/libc/include/sys/cdefs.h
index 48763d7..1d33895 100644
--- a/libc/include/sys/cdefs.h
+++ b/libc/include/sys/cdefs.h
@@ -335,13 +335,15 @@
 #endif
 
 #if __GNUC_PREREQ(4, 3)
-#define __errordecl(name, msg) extern void name(void) __attribute__((__error__(msg)))
+#define __errorattr(msg) __attribute__((__error__(msg)))
 #define __warnattr(msg) __attribute__((__warning__(msg)))
 #else
-#define __errordecl(name, msg) extern void name(void)
+#define __errorattr(msg)
 #define __warnattr(msg)
 #endif
 
+#define __errordecl(name, msg) extern void name(void) __errorattr(msg)
+
 /*
  * Some BSD source needs these macros.
  * Originally they embedded the rcs versions of each source file