This patch adds the new UDP_ENCAP_GTP0 and UDP_ENCAP_GTP1U from Linux
4.7 to sysdeps/gnu/netinet/udp.h.
Tested for x86_64 and x86 (testsuite, and that installed stripped
shared libraries are unchanged by the patch).
* sysdeps/gnu/netinet/udp.h (UDP_ENCAP_GTP0): New macro.
(UDP_ENCAP_GTP1U): Likewise.