It was a bad idea to have the #ifdef MOZ_GSTREAMER in the middle of the include files, it probably has something to do with the line continuation character just before the #ifdef – I’m not familiar with the pass steps for a makefile, but obviously it was messed up 🙂 so away they go, now using just:

-I$(srcdir)/../../../../gstreamer/gstreamer-0.10.22 \
-I/usr/include/glib-2.0 \
-I/usr/include/glib-2.0/include \
-I/usr/lib/glib-2.0/include \