re PR c++/82294 (Array of objects with constexpr constructors initialized from space-inefficient memory image)

	PR c++/82294
	PR c++/87436
	* expr.h (categorize_ctor_elements): Add p_unique_nz_elts argument.
	* expr.c (categorize_ctor_elements_1): Likewise.  Compute it like
	p_nz_elts, except don't multiply it by mult.  Adjust recursive call.
	Fix up COMPLEX_CST handling.
	(categorize_ctor_elements): Add p_unique_nz_elts argument, initialize
	it and pass it through to categorize_ctor_elements_1.
	(mostly_zeros_p, all_zeros_p): Adjust categorize_ctor_elements callers.
	* gimplify.c (gimplify_init_constructor): Likewise.  Don't force
	ctor into readonly data section if num_unique_nonzero_elements is
	smaller or equal to 1/8 of num_nonzero_elements and size is >= 64
	bytes.

	* g++.dg/tree-ssa/pr82294.C: New test.
	* g++.dg/tree-ssa/pr87436.C: New test.

From-SVN: r267143