Default ISA/tuning flags for GCC, --enable-kernel= level for glibc

[Bill Nottingham]

Jakub Jelinek (jakub at redhat.com) said: 
> > There is no plan for 31-bit Fedora on s390 AFAIK, and regarding 64-bit
> > please take a look at https://bugzilla.redhat.com/show_bug.cgi?id=463830
> 
> If we are to use -march=z9-109 -mtune=z10 instead of -march=z900 -mtune=z10
> for s390 -m31 and -m64, then releng is important.  Aren't the current
> mainframes used for Fedora (and RHEL) building z990?  If yes, then this
> can't be switched until they are z9-109 or z10 based.

They appear to be z9-109.

Bill