Missing glib2.0 requirement in spice-client-glib-2.0 and spice-client-gtk-3.0 pkg-config files

Hello,

In the generated spice-client-glib-2.0 pkg-config file, glib (and gio) are only in the Requires.private but its headers are using headers file from glib.

It should be moved to Requires instead

As the file is generated, that should be done at meson level

Edit: Same problem for spice-client-gtk-3.0 pkg-config file