[GTK] Add Clutter to jhbuild
https://bugs.webkit.org/show_bug.cgi?id=110245

Reviewed by Martin Robinson.

Add clutter, cogl, clutter-gtk, and atk to the optional moduleset.
This allows to build WebKitGtk+ with clutter as an acceleration backend
within the jhbuild environment.

* gtk/jhbuild-optional.modules:


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144028 268f45cc-cd09-0410-ab3c-d52691b4dbfc