Fix #34694. This was actually a bug in the compositor's Bokeh Blur operation. It was writing outside of allocated memory in case of (0, 0) size buffers, with the usual unpredictable results.

git-svn-id: https://svn.blender.org/svnroot/bf-blender/trunk/blender@55444 954f8c5b-7b00-dc11-b283-0030488c597c