[build] List cogl-internal.h
[build] List cogl-internal.h

During the Makefile clean up, cogl-internal.h got lost and this
broke the dist. Let's put it back in.

djdeath/clutter-multithreaded,tardyp/clutter,collects/clutter,rkudiyarov/clutter_osx,GNOME/clutter,djdeath/clutter-android,kerrickstaley/clutter-vala,heysion/clutter-clone,jigpu/clutter,djdeath/clutter,spatulasnout/clutter,collects/clutter,djdeath/clutter-android,Distrotech/clutter,Distrotech/clutter,collects/clutter,GNOME/clutter,heysion/clutter-clone,djdeath/clutter-android,ebassi/clutter,djdeath/clutter-android,kerrickstaley/clutter-vala,ebassi/clutter,Distrotech/clutter,djdeath/clutter,heysion/clutter-clone,djdeath/clutter,nobled/clutter,tardyp/clutter,collects/clutter,collects/clutter,spatulasnout/clutter,Distrotech/clutter,GNOME/clutter,GNOME/clutter,nobled/clutter,ebassi/clutter,nobled/clutter,djdeath/clutter,rkudiyarov/clutter_osx,djdeath/clutter,dlespiau/clutter,rkudiyarov/clutter_osx,kerrickstaley/clutter-vala,ebassi/clutter,spatulasnout/clutter,jigpu/clutter,ebassi/clutter,heysion/clutter-clone,jigpu/clutter,djdeath/clutter-multithreaded,dlespiau/clutter,Distrotech/clutter,tardyp/clutter,djdeath/clutter,heysion/clutter-clone,rkudiyarov/clutter_osx,kerrickstaley/clutter-vala,GNOME/clutter,jigpu/clutter,spatulasnout/clutter,djdeath/clutter-android,spatulasnout/clutter,dlespiau/clutter,djdeath/clutter-multithreaded,jigpu/clutter,Distrotech/clutter,djdeath/clutter-multithreaded,jigpu/clutter