ass.h: Mark deprecated declarations as deprecated
ass.h: Mark deprecated declarations as deprecated

GCC, Clang and MSVC now issue a warning when deprecated API is used.

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