Switch to GDBus

[NovaAndrom3da]

According to the official dbus-glib documentation, it is obsolete and replaced by GDBus.

[EarldridgeJazzedPineda]

dbus-glib isn't used in the source code anymore, and there are only three remaining mentions of it:

mate-settings-daemon/configure.ac

Line 55 in a007205

DBUS_GLIB_REQUIRED_VERSION=0.74

mate-settings-daemon/data/mate-settings-daemon.pc.in

Line 11 in a007205

Requires: glib-2.0 dbus-1 dbus-glib-1

mate-settings-daemon/data/mate-settings-daemon-uninstalled.pc.in

Line 9 in a007205

Requires: glib-2.0 dbus-1 dbus-glib-1

[lukefromdc]

It should thus be easy to remove those three unused references

[lukefromdc]

#420
removes those remnants. The actual code was changed over during the 1.27 development cycle