Revert "Remove unused basegfx::tools::containsOnlyHorizontalAndVerticalEdges"

Is used in vcl/win/source/gdi/salgdi.cxx.

This reverts commit 34fa29ed4c0fa73d3e07e62cb6ca2577ee115b35.

Conflicts:
	unusedcode.easy

Change-Id: I0ee3c2bc0ec5649045ae415b44482f63da360634