gdk_x11_display_utf8_to_compound_text

Compound text is dead technology and fully obsoleted by UTF actually. Do
not claim support for it if not on X11. This should fix the crash.

Change-Id: Id4df68bc3e2052eee88f22a3b06c94537cc6899a
Signed-off-by: Alexander Kurtakov <akurtako@redhat.com>