Cleanups

* Get rid of members in QQmlCompiledData that were used by the VME
  and are now unused
* Get rid of QQmlVME friend declarations that are not needed anymore

Change-Id: I11b4b6f0b4b0b60edf92a1256be3d0d44d76bbc9
Reviewed-by: Lars Knoll <lars.knoll@digia.com>