[aat.morx] Remove set_object() business

With OS X 10.13 Apple Chancery fails to ligate if we limit each morx
sub-chain to its declared length.  Perhaps their newer compiler does
object-sharing across sub-chains.  Anyway, since that's a valid, if
unspecified, way to compile tables, remove enforcement.

Probably do the same with kern/kerx.
1 file changed