gitignore: Update the path of generated GLES2 shaders
gitignore: Update the path of generated GLES2 shaders

The generation is not happening in the main Cogl directory, Update the
.gitignore file accordingly.

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