VclPixelProcessor2D: the constructor changes the anti-aliasing mode of
the given output device, and the destructor restores a hard-coded mode
instead of what was there before.

Due to this commit 5913506b turned off
anti-aliasing for FontWork objects simply by creating a
temporary VclPixelProcessor2D.

Change-Id: I7f7fcbf86b0dd425f599cd8e62fce3c69a2744bb