Fortran bootstrap failure (was [patch, libfortran] AMD-specific versions of library matmul)

[Wilco Dijkstra]

Hi,

This patch most likely broke all non-x86 targets:
configure: error: conditional "HAVE_AVX128" was never defined.
Usually this means the macro was only invoked conditionally.
Makefile:19843: recipe for target 'configure-target-libgfortran' failed
make[1]: *** [configure-target-libgfortran] Error 1
make[1]: *** Waiting for unfinished jobs....

I've created PR80889 for this. It would be good to either fix or revert this asap
as otherwise we lose all testing for the next 3 days too...

Wilco