Revert "Silence GCC warning variable ‘max_size’ set but not used"

Based on chief1983's comment that this code is still used, I'll take
the safer route of just telling gcc to shaddupaboudit

git-svn-id: svn://svn.icculus.org/fs2open/trunk/fs2_open@11029 387891d4-d844-0410-90c0-e4c51a9137d3