[Ada] Plug small loophole with pathological packed array type

[Ada] Plug small loophole with pathological packed array type

This fixes a crash in gigi on a pathological packed array type, whose
component type is a record type without representation clause or packing
but with a clause that bumps its size to a non-multiple value of the
storage unit.  In this case, the front-end fails to detect that calls
to the packing manpulation routines of the run time are necessary.

The fix doesn't change anything for non-pathological cases, i.e. when
the component type has a representation clause or is packed.

2018-12-11  Eric Botcazou  <ebotcazou@adacore.com>

gcc/ada/

	* exp_aggr.adb (Packed_Array_Aggregate_Handled): Bail out for
	any non-scalar type as component type of the array.

gcc/testsuite/

	* gnat.dg/packed_array.adb, gnat.dg/packed_array.ads,
	gnat.dg/packed_array_pkg.ads: New testcase.

From-SVN: r267006