Try building 9.0.1

Enable the compiler optimizations that were crashing qemu-user with LLVM
9 to see if the situation is improved with LLVM 10.
2 jobs for main in 6 minutes and 14 seconds (queued for 1 second)
Status Job ID Name Coverage
  Build
failed Build arm64 #750
nest

00:06:14

canceled Build arm64 #727
nest

00:33:02

 
Name Stage Failure
failed
Build arm64 Build

The following REQUIRED_USE flag constraints are unsatisfied:
?? ( ghcbootstrap binary )

The above constraints are a subset of the following complete expression:
at-most-one-of ( ghcbootstrap binary ) at-most-one-of ( profile binary ) arm? ( llvm )

Cleaning up file based variables
ERROR: Job failed: exit code 1