Bump mate-desktop required to version 1.9.4

The materr* changes are not in mate-desktop 1.9.3 yet.
Add back Glib 2.32 support
Revert "Add back Glib 2.32 support"

This reverts commit 602945c084d45bd3858e564e03a70a2a361a5756.
fix paths in .pc file
remove erroneous code