REDHAT-BUG-639356: High severity Freedesktop poppler vulnerability

poppler git commit bf2055088a corrects a possible use of an uninitialized pointer in PostScriptFunction, which can cause crash or memory corruption.

Upstream git commit: http://cgit.freedesktop.org/poppler/poppler/commit/?id=bf2055088a3a2d3bb3d3c37d464954ec1a25771f

This problem does not affect xpdf or other applications embedding xpdf code. It only affects recent poppler versions, not before commit:

http://cgit.freedesktop.org/poppler/poppler/commit/?id=b1d4efb082ac3dadd7752a557e5aeb6651e17471

Reference: http://secunia.com/advisories/41596/