ada: Fix wrong finalization of constrained subtype of unconstrained array type

ada: Fix wrong finalization of constrained subtype of unconstrained array type

This implements the Is_Constr_Array_Subt_With_Bounds flag for allocators.

gcc/ada/ChangeLog:

	* gcc-interface/trans.cc (gnat_to_gnu) <N_Allocator>: Allocate the
	bounds alongside the data if the Is_Constr_Array_Subt_With_Bounds
	flag is set on the designated type.
	<N_Free_Statement>: Take into account the allocated bounds if the
	Is_Constr_Array_Subt_With_Bounds flag is set on the designated type.