Various small C++ fixes.

Various small C++ fixes.

	* typeck.c (condition_conversion): Assert !processing_template_decl.
	* semantics.c (finish_omp_clauses): Don't
	fold_build_cleanup_point_expr if processing_template_decl.
	(outer_var_p): A temporary can't be from an outer scope.
	* pt.c (type_dependent_expression_p): Fix dependency checking of
	functions without DECL_TEMPLATE_INFO.
	(instantiate_decl): Use lss_copy.
	* constexpr.c (is_valid_constexpr_fn): Fix lambdas before C++17.

From-SVN: r253600