git-daemon-sysvinit: mark /etc/init.d/git-daemon as dpkg conffile

git-daemon-sysvinit: mark /etc/init.d/git-daemon as dpkg conffile

Debian policy §9.3.2 sayeth:

	The /etc/init.d scripts must be treated as configuration
	files, either (if they are present in the package, that is, in
	the .deb file) by marking them as conffiles, or, (if they do
	not exist in the .deb) by managing them correctly in the
	maintainer scripts (see Configuration files, Section 10.7).
	This is important since we want to give the local system
	administrator the chance to adapt the scripts to the local
	system [...].

Make it so.  The downside is that the init script is not removed on
package removal so the following sequence of events:

	install git-daemon-sysvinit
	enable git-daemon-sysvinit in /etc/default
	remove git-daemon-sysvinit (but do not purge it)
	reboot

leaves git-daemon running.  That can be fixed later.

[jn: with new change description]

Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>