Activating FFT multiplication *still not ideally optimised) for
Here I tidy up after ye4sterdays big checkin so that now the --with-arithlib
A load of CSL files are changed here nut at least in principle not a lot
Instead of using the C++ "high_resolution_clock" I now used the "steady_clock"
fftmod.cpp and cthread.cpp are freestanding at present but I intend to
Add a new file cthread.cpp
iMake the gf2 package build under PSL, even if its output is not consistent
The forthcoming Fedora 43 seems to defined an "extern double rsqrt()" and