Replace std::vector<> usage in ipa-fnsummary.c with GCC's vec<>.

gcc/ChangeLog:

	* ipa-fnsummary.c (evaluate_conditions_for_known_args): Use vec<>
	instead of std::vector<>.
	(evaluate_properties_for_edge): Same.
	(ipa_fn_summary_t::duplicate): Same.
	(estimate_ipcp_clone_size_and_time): Same.
	* vec.h (<T, A, vl_embed>::embedded_size): Change vec_embedded
	type to contain a char[].