Simon McVittie authored Apr 06, 2016 and Simon McVittie committed Apr 13, 2016

I've implemented this by adding a --with[out]-systemduserunitdir
configure option, because that seems to be what's conventional
in projects where user units are configurable at all. If a user or
distribution wants to disable these units, it's easier if they can
pass --without-systemduserunitdir to everything, rather than checking
whether it's spelled --disable-systemd-user-units in this particular
project. Also, a binary enable/disable option wouldn't be noticeably
less code.

If the systemd user unit is disabled at configure time, the
SystemdService line in the installed D-Bus service file is commented
out. This addresses the corner-case situation where a user configures
Evince --without-systemduserunitdir, but enables systemd activation
for their session dbus-daemon (perhaps later). In that situation,
we presumably want Evince to continue to use traditional activation,
rather than trying to launch a nonexistent systemd unit.

Signed-off-by: Simon McVittie <simon.mcvittie@collabora.co.uk>
Bug: https://bugzilla.gnome.org/show_bug.cgi?id=755897
Reviewed-by: Carlos Garcia Campos