clutter: rename to clutter-glx so we can have different flavours of clutter

* Needs a fix for pkgconfig, but it's a nice first step

diff --git a/packages/clutter/clutter_svn.bb b/packages/clutter/clutter-glx_svn.bb
similarity index 100%
rename from packages/clutter/clutter_svn.bb
rename to packages/clutter/clutter-glx_svn.bb