Cheat files: If no disc is inserted, treat CRC as 00000000 when trying to load pnach files (previously, empty CRC would result in *.pnach wildcard, which tried to load all pnach files).

git-svn-id: http://pcsx2.googlecode.com/svn/trunk@5614 96395faa-99c1-11dd-bbfe-3dabce05a288