lxdm: fix postinst-code

Exiting postinst code leaves systemd.bbclass offline postinst code unexecuted,
causes postinst not to finish at first boot (lxdm.service is not aliased to
display-manager.service -> started much too early) and is not neccesary:
language preparation can be done offline.

Signed-off-by: Andreas Müller <schnitzeltony@googlemail.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
gnome-keyring: add (from oe-core)

This was previously in oe-core but nothing there was actually using it in an
image.  As it's part of GNOME, move it meta-gnome.

The custom service file is dropped, as upstream is now shipping and installing
this file (and has been for some time).

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>
libgnome-keyring: add (from oe-core)

This was in oe-core previously but it's not actually used by anything:
webkit-gtk claimed a false dependency and the new libsoup has removed all use of
gnome-keyring.

Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Martin Jansa <Martin.Jansa@gmail.com>