Simplify ass_utils.c code
Simplify ass_utils.c code

Mainly cosmetic, but maybe some optimizations the compiler misses.

Akemi/libass,sanyaade-g2g-repos/libass,astiob/libass,MrSmile/libass,Akemi/libass,torque/libass,mwgoldsmith/libass,pigoz/libass-ct,libass/libass,libass/libass,stps/libass,pigoz/libass-ct,grigorig/libass,ShiftMediaProject/libass,mwgoldsmith/libass,xbmc/libass,MrSmile/libass,pigoz/libass-ct,ShiftMediaProject/libass,astiob/libass,sanyaade-g2g-repos/libass,grigorig/libass,xbmc/libass,Akemi/libass,stps/libass,mwgoldsmith/libass,stps/libass,sanyaade-g2g-repos/libass,torque/libass,torque/libass