Linux 4.8 adds TCP_REPAIR_WINDOW to include/uapi/linux/tcp.h. This
patch adds it to sysdeps/gnu/netinet/tcp.h accordingly, along with
struct tcp_repair_window as requested in
<https://sourceware.org/ml/libc-alpha/2016-10/msg00019.html>.
Tested for x86_64 and x86 (testsuite, and that installed shared
libraries are unchanged by the patch).
* sysdeps/gnu/netinet/tcp.h (TCP_REPAIR_WINDOW): New macro.
(struct tcp_repair_window): New type.