configure: Remove superfluous comma
configure: Remove superfluous comma

AC_LANG_PROGRAMM only takes two parameters.

Akemi/libass,MrSmile/libass,astiob/libass,ShiftMediaProject/libass,libass/libass,Akemi/libass,ShiftMediaProject/libass,xbmc/libass,astiob/libass,Akemi/libass,xbmc/libass,MrSmile/libass,libass/libass