[patch, libfortran] AMD-specific versions of library matmul

[Thomas Koenig]

Hi Jerry,

> Yes, OK.  Maybe test Ryzen first?

Sure, I can wait for a bit :-)
> I just confirmed access to the Ryzen machines so I plan to get set up 
> and test there.

The gcc compile farm machines?  My ssh key does not work there...

I have based the choice of FMA(3) over FMA4 when both are available
on a short remark in a benchmark that FMA3 is faster... it might
be interesting to see if that is actually true.

Regards

	Thomas