mtd-utils: serve_image: use proper POSIX_C_SOURCE value struct addrinfo and friends conform to POSIX.1-2001, not earlier. This patch fixes linking against latest glibc 2.22 Signed-off-by: Kirill Smirnov <kirill.k.smirnov@gmail.com> Signed-off-by: Brian Norris <computersforpeace@gmail.com>