Fix builds where _FORTIFY_SOURCE is off.

Also add a more intention-revealing guard so we don't have loads of
places checking whether our inlining macro is defined.

Change-Id: I168860cedcfc798b07a5145bc48a125700265e47

libc/include/strings.h

@@ -50,12 +50,12 @@ char	*index(const char *, int);
 int	 strcasecmp(const char *, const char *);
 int	 strncasecmp(const char *, const char *, size_t);
 
-#if defined(__BIONIC_FORTIFY_INLINE)
+#if defined(__BIONIC_FORTIFY)
 __BIONIC_FORTIFY_INLINE
 void bzero (void *s, size_t n) {
     __builtin___memset_chk(s, '\0', n, __builtin_object_size (s, 0));
 }
-#endif /* defined(__BIONIC_FORTIFY_INLINE) */
+#endif /* defined(__BIONIC_FORTIFY) */
 
 __END_DECLS