llvm on aarch64 builds very slowly

[Ricardo Wurmus]

Hi Guix,

I had to manually run the build of llvm 11 on aarch64, because it would
keep timing out:

    time guix build /gnu/store/0hc7inxqcczb8mq2wcwrcw0vd3i2agkv-llvm-11.0.0.drv 
--timeout=999999 --max-silent-time=999999

After more than two days it finally built.  This seems a little
excessive.  Towards the end of the build I saw a 1% point progress
increase for every hour that passed.

Is there something wrong with the build nodes, are we building llvm 11
wrong, or is this just the way it is on aarch64 systems?

-- 
Ricardo