clean up FORTIFY_SOURCE handling.

Avoid duplicating huge chunks of code.

Change-Id: Id6145cdfce781c5ffba2abaaa79681d25a7ab28f
diff --git a/libc/string/strrchr.c b/libc/string/strrchr.c
index fc3dc4e..5d0415e 100644
--- a/libc/string/strrchr.c
+++ b/libc/string/strrchr.c
@@ -37,11 +37,8 @@
 	char *save;
 
 	for (save = NULL;; ++p, s_len--) {
-		if (s_len == 0) {
-			__libc_android_log_print(ANDROID_LOG_FATAL, "libc",
-				"*** FORTIFY_SOURCE strrchr read beyond buffer ***\n");
-			abort();
-		}
+		if (s_len == 0)
+			__fortify_chk_fail("strrchr read beyond buffer", 0);
 		if (*p == (char) ch)
 			save = (char *)p;
 		if (!*p)