[Bug c/99291] maybe_warn_pass_by_reference uses outdated format string

[roland.illig at gmx dot de via Gcc-bugs]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99291

--- Comment #3 from Roland Illig <roland.illig at gmx dot de> ---
same file, another one:
> "version of `g` will be omitted, please "

This is far from any coding conventions and should rather be %<g%>.