[cogl-material] Restore the GL_TEXTURE_ENV_MODE after material_rectangle
[cogl-material] Restore the GL_TEXTURE_ENV_MODE after material_rectangle

The rest of Cogl expects the texture mode to be GL_MODULATE so it
needs to be restored after calling cogl_material_rectangle. Otherwise
cogl_texture_rectangle will fail to blend with the Cogl color properly
and all of the labels will be black.

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