COMP: Ensure teem is properly link against png if CMake > 2.8.11.2 is used

See inlined comment for more details.

Associated discussion: http://massmail.spl.harvard.edu/public-archives/slicer-devel/2013/thread.html#13536

Fixes #3369

Co-authored-by: Steve Pieper <pieper@bwh.harvard.edu>
Co-authored-by: James Cook <james.j.cook@duke.edu>

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22411 3bd1e089-480b-0410-8dfb-8563597acbee