Fix gio_module_dir with some wrong gio-2.0.pc
Fix gio_module_dir with some wrong gio-2.0.pc

For example fedora 29's gio-2.0.pc defines libdir=/usr/lib64 instead of
libdir=${prefix}/lib64

GNOME/glib-networking,GNOME/glib-networking,GNOME/glib-networking