PR c++/38030, 38850, 39070
* pt.c (type_dependent_expression_p_push): New fn.
(tsubst_copy_and_build) [CALL_EXPR]: Only do arg-dep lookup when the
substitution makes the call non-dependent. Preserve koenig_p.
* parser.c (cp_parser_postfix_expression): Only do arg-dep lookup
for non-dependent calls.
* semantics.c (finish_call_expr): Revert earlier changes.
* cp-tree.h: Revert change to finish_call_expr prototype.