preprocessor: Further fix for EOF in macro args [PR97471]

My previous attempt at fixing this was incorrect.  The problem occurs
earlier in that _cpp_lex_direct processes the unwinding EOF needs in
collect_args mode.  This patch changes it not to do that, in the same
way as directive parsing works.  Also collect_args shouldn't push_back
such fake EOFs, and neither should funlike_invocation_p.

	libcpp/
	* lex.c (_cpp_lex_direct): Do not complete EOF processing when
	parsing_args.
	* macro.c (collect_args): Do not unwind fake EOF.
	(funlike_invocation_p): Do not unwind fake EOF.
	(cpp_context): Replace abort with gcc_assert.
	gcc/testsuite/
	* gcc.dg/cpp/endif.c: Move to ...
	* c-c++-common/cpp/endif.c: ... here.
	* gcc.dg/cpp/endif.h: Move to ...
	* c-c++-common/cpp/endif.h: ... here.
	* c-c++-common/cpp/eof-2.c: Adjust diagnostic.
	* c-c++-common/cpp/eof-3.c: Adjust diagnostic.