[OE-core] further colg/clutter improvements and fixes

[Tomas Frydrych]

These patches take on board Ross feedback on the previous patch set, removing
unnecessary gtk-doc bits from the receipes, as well as the configure fragments
related to DOLT. Also, more of the configure parameters have been moved into
the PACKAGECONFIG definitions.

While modifying the PACKAGECONFIG, I noticed a typo in the cogl recipe that 
effected the RDEPENDS setup for the 'gl' option, and also a missing comma 
in the 'glx' setup for clutter, so these are fixed as well.

[PATCH 1/4] clutter.bbclass: removed unused function
[PATCH 2/4] cogl: further improvements
[PATCH 3/4] clutter: further improvements
[PATCH 4/4] clutter-gst: removed no longer required configure