[Spice-devel] fix build with glib < 2.32

[nicolas prochazka]

hello
patch from Marc-André Lureau :

[Spice-devel] [PATCH spice-gtk 1/2] build: fix build with glib < 2.32

does not cover
channel-usbredir.c  file

compilation is not possible.

Regards,
Nicolas Prochazka.