[PATCH] Fix -H vs. PCH (PR preprocessor/36649)

[Tom Tromey]

>>>>> "Jakub" == Jakub Jelinek <jakub@redhat.com> writes:

Jakub> The following patch fixes it by saving/restoring the
Jakub> line_table-> trace_includes
Jakub> setting around PCH reading, similarly how e.g. location is saved.

It looks good to me -- though I can't approve patches in c-pch.c.

I have occasionally wondered why this work is done here and not in
cpp_read_state.  However, given that there is already code in c-pch.c
to save and restore something, I think it doesn't hurt to add more.

Tom