[Bug preprocessor/61638] "warning: multi-line comment" unclear and has false positives

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61638

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(Changed from "enhancement" to "normal" because the current behaviour is just
bad)