swift234

retype emitGetAccessor/emitSetAccessor to take an AbstractStorageDecl
instead of a ValueDecl (which is more specific).  This allows them to
use the more specific ASD::usesObjCGetterAndSetter() method instead
of SGM::requiresObjCDispatch.

To enable this, push AbstractStorageDecl through SILGenLValue's
GetterSetterComponent.


Swift SVN r12578