Add a configure check for -Wno-fortify-source to suppress Clang warnings
on string/tester.c, like:
tester.c:385:10: error: 'strncat' size argument is too large; destination buffer has size 50, but size argument is 99 [-Werror,-Wfortify-source]
385 | check (strncat (one, "lmn", 99) == one, 1); /* Returned value. */
Signed-off-by: H.J. Lu <hjl.tools@gmail.com>
Reviewed-by: Sam James <sam@gentoo.org>