c++: Reduce memory consumption for arrays of non-aggregate type.

c++: Reduce memory consumption for arrays of non-aggregate type.

The remaining low-hanging fruit for improvement on memory consumption in the
14179 testcase was the duplication of the CONSTRUCTOR for the array by
reshape_init.  This patch changes reshape_init to reuse a single constructor
for an array of non-aggregate type such as the one in the testcase.

	PR c++/14179
	* decl.c (reshape_init_array_1): Reuse a single CONSTRUCTOR with
	non-aggregate elements.
	(reshape_init_array): Add first_initializer_p parm.
	(reshape_init_r): Change first_initializer_p from bool to tree.
	(reshape_init): Pass init to it.