gck: Expose gck_mechanisms_check() in Vala
Add a basic PKCS#11 VAPI file
gcr: Make GcrComparable introspectable as an interface
gck: Properly expose introspectable gck_builder_add_only()
gck: Define GCK_INVALID as a gulong, for easier introspection
gck: Properly flag (out) arguments for introspection
gcr: More vapi fixes for GcrComparable