git-daemon: set REMOTE_ADDR to client address

git-daemon: set REMOTE_ADDR to client address

This allows hooks like pre-receive to look at the client's IP
address.

Of course the IP address can't be used to get strong security;
git-daemon isn't the right thing to use if you need that. However,
basic IP address checking can be good enough in some situations.

REMOTE_ADDR is the same environment variable used to communicate the
client's address to CGI scripts.

Signed-off-by: Joey Hess <joey@kitenet.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>