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.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@253600 138bc75d-0d04-0410-961f-82ee72b054a4