preprocessor: Fix ICE with EOF in macro args [pr95182]

This was another latent case of us losing an EOF token, but succeeding
anyway.  Since my patch to make us pay more attention to EOFs it came
to light.  We also need to keep the EOF if we fall off the end of the
main file.  Forced includes look like regular nested includes at this
point.

	PR preprocessor/95182
	libcpp/
	* macro.c (collect_args): Preserve EOFif we fell out of the main
	file.
	(cpp_get_token_1): Reformat a couple of short lines.