Fix for memcpy() and strcmp() being undefined.

clang says: "s_cb.c:958:9: error: implicitly declaring library function
'memcpy'"

Reviewed-by: Rich Salz <rsalz@openssl.org>
Reviewed-by: Richard Levitte <levitte@openssl.org>
(cherry picked from commit 8f744cce)

Conflicts:
	apps/s_cb.c