bug#25987: 25.2; support gcc fixit notes

[Eli Zaretskii]

> From: Tom Tromey <tom@tromey.com>
> Cc: Tom Tromey <tom@tromey.com>,  25987@debbugs.gnu.org
> Date: Wed, 08 Mar 2017 11:34:38 -0700
> 
> Tom> I'll see if I can find out the rationale.
> 
> Eli> Thanks.
> 
> The reason is compatibility with clang, which had this option first.
> http://releases.llvm.org/3.8.0/tools/clang/docs/UsersManual.html#cmdoption-fdiagnostics-parseable-fixits

Thanks.  So maybe GCC should have a similar option, named differently,
which would report in characters.

Anyway, "we have the technology" in Emacs to deal with this.