glib-compile-schemas: Handle per-desktop overrides
glib-compile-schemas: Handle per-desktop overrides

Add a new syntax to override files: if the group name has a ':' in it,
it indicates that we want to override the default values of keys for
only one desktop. For example:

[org.gnome.desktop.interface:Unity]
font-name='Ubuntu 12'

Will override the settings, only if "Unity" is found in
XDG_CURRENT_DESKTOP. Multiple per-desktop overrides can be specified
for a given key: the one which comes first in XDG_CURRENT_DESKTOP will
be used.

https://bugzilla.gnome.org/show_bug.cgi?id=746592

endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib,endlessm/glib