ada: Fix crash on aliased variable with packed array type and -g switch

ada: Fix crash on aliased variable with packed array type and -g switch

This comes from a loophole in gnat_get_array_descr_info for record types
containing a template, which represent an aliased array, when this array
type is bit-packed and implemented as a modular integer.

gcc/ada/

	* gcc-interface/misc.cc (gnat_get_array_descr_info): Test the
	BIT_PACKED_ARRAY_TYPE_P flag only once on the final debug type. In
	the case of records containing a template, replay the entire
	processing for the array type contained therein.