mi: Use GC clipregion instead of drawable in miDoCopy/miCopyArea
As discussed in issue #829 (closed) the "mi: Shortcut miDoCopy/miCopyArea based on clipList" change leads to pointer-trails (area under pointer not restored when it moves) when using a software cursor.
Checking pGC->pCompositeClip instead of pDstDrawable->clipList fixes this problem.
Fixes: #829 (closed)
Edited by Hans de Goede