re PR c++/70001 (Infinity compilation time)

re PR c++/70001 (Infinity compilation time)

	PR c++/70001
	* constexpr.c (cxx_eval_vec_init_1): For pre_init case, reuse
	return value from cxx_eval_constant_expression from earlier
	elements if it is valid constant initializer requiring no
	relocations.

	* g++.dg/cpp0x/constexpr-70001-1.C: New test.
	* g++.dg/cpp0x/constexpr-70001-2.C: New test.
	* g++.dg/cpp0x/constexpr-70001-3.C: New test.

Co-Authored-By: Jakub Jelinek <jakub@redhat.com>
From-SVN: r234117