Document PR 84073 change in /gcc-8/porting_to.html

[Thomas Koenig]

Am 10.05.2018 um 12:33 schrieb Jonathan Wakely:
> Should the fix for PR 84073 be documented, so that users whose code is
> now rejected understand why, and how to fix it?
> 
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=84073
> https://gcc.gnu.org/gcc-8/porting_to.html#fortran

Sounds like a good idea.

Since I introduced this, I'll do it within a few days (unless, of
course, somebody beats me to it, which I won't mind :-)

Regards

	Thomas