gobject_gdb.py: support gsignal fastpath and detect more marshallers

• Commit f02ec2f2 added a gsignal fastpath where g_closure_invoke_va() is directly called from g_signal_emit_valist() skipping signal_emit_unlocked_R() altogether which it's the function used by gobject_gdb.py to detect signal emission.

  So we update gobject_gdb.py to also detect signals which use this g_closure_invoke_va() fastpath.

• We also update the code that detects marshallers to also include these:

  surface_event_marshaller()
gdk_surface_event_marshallerv()
g_type_class_meta_marshal()
g_type_class_meta_marshalv()

  This allow us that for signal emissions which use those marshallers to keep showing the signal handler frame just after the <emit signal blabla> line.

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