Where is libquadmath on slarm64?

I am trying to build FlatCAM on my rpi4 which has slarm64 installed on it. One of the many dependancies has complained that it can't libquadmath.h. It is not there but on my slackware64 machine it is part of gcc. Should it be part of gcc on aarch64 or is it only x86. I will try a build of gcc to see what happens but that will take some time.

regards Dunc.