Merge branch 'ew/daemon-socket-keepalive'

Recent update to "git daemon" tries to enable the socket-level
KEEPALIVE, but when it is spawned via inetd, the standard input
file descriptor may not necessarily be connected to a socket.
Suppress an ENOTSOCK error from setsockopt().

* ew/daemon-socket-keepalive:
  Windows: add missing definition of ENOTSOCK
  daemon: ignore ENOTSOCK from setsockopt

diff --cc compat/mingw.h
Simple merge

diff --cc daemon.c
Simple merge