completely avoid usage of strnlen()

strutil.h

@@ -43,9 +43,4 @@ extern int
 maxlen_snprintf(char *str, const char *format,...)
 __attribute__((format(PG_PRINTF_ATTRIBUTE, 2, 3)));
 
-/* Add strnlen on platforms that don't have it, like OS X */
-#ifndef strnlen
-extern size_t strnlen(const char *s, size_t n);
-#endif
-
 #endif   /* _STRUTIL_H_ */