Use on M1 with latest docker (v3.3.1)

[mschrettenbrunner]

build stops with ...

PLEASE submit a bug report to https://bugs.llvm.org/ and include the crash backtrace.
Stack dump:

0.  Program arguments: /usr/bin/swift -v build --product HelloWorld -c release 
   

1.  Swift version 5.4-dev (LLVM 7a20f40c45aca5d, Swift 031b848b7092c06)
   

/usr/bin/swift[0x57fd9f4]
/usr/bin/swift[0x57fb4ee]
/usr/bin/swift[0x57fdbdc]
/lib64/libpthread.so.0(+0x117e0)[0x4000a3e7e0]
/usr/bin/swift[0x1af669c]
/usr/bin/swift[0x1af051f]
/usr/bin/swift[0x49f4d7]
/usr/bin/swift[0x49e8aa]
/lib64/libc.so.6(__libc_start_main+0xea)[0x4001f990ba]
/usr/bin/swift[0x49e3da]
qemu: uncaught target signal 4 (Illegal instruction) - core dumped

[mschrettenbrunner]

... following docker/for-mac#5561 with "export QEMU_CPU=max" I got the build done