coretext: fix reading weights of some fonts
coretext: fix reading weights of some fonts

Some fonts have weights that can be expressed more precisely as doubles than
as floats. In these cases, when writing to a float, CFNumberGetValue will set
the value to the closest approximation, but return false (so we'd just clobber
whatever it set with 0). Easy fix: just store to a double instead.

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