enabled (not enough registers), so for now, we only build it if we see
 the __OPTIMIZE__ #define, which GCC provides when you build at -O1 or higher.

--HG--
branch : SDL-1.2
extra : convert_revision : svn%3Ac70aab31-4412-0410-b14c-859654838e24/branches/SDL-1.2%402527