ada: Fix wrong indirect access to bit-packed array in iterated loop

ada: Fix wrong indirect access to bit-packed array in iterated loop

This comes from a missing expansion of the bit-packed array reference in
the loop, because the actual subtype created for the dereference lacks a
Packed_Array_Impl_Type as it is ultimately created by the Preanalyze_Range
call present in Analyze_Loop_Statement.

gcc/ada/ChangeLog:

	* sem_util.adb (Get_Actual_Subtype): Only create a new subtype when
	the expander is active.  Remove a useless test of type inequality,
	as well as a useless call to Set_Has_Delayed_Freeze on the subtype.