go 1.18 fails to build on macOS

@pierov ran into this issue while we were attempting to build alpha 11.5a8:

Opening log file: Thu Mar 17 19:08:27 2022
Starting build (script: build): 2022-03-17 19:08:28
# golang.org/x/sys/unix
unix/zsyscall_darwin_amd64.go:28:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:43:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:59:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:75:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:90:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:105:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:121:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:136:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:151:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:166:3: //go:linkname must refer to declared function or variable
unix/zsyscall_darwin_amd64.go:166:3: too many errors
Finishing build (script: build): 2022-03-17 19:08:33
Build time: 0 hours 0 minutes and 5 seconds

Some initial googling points us to: https://stackoverflow.com/questions/71507321/go-upgrade-to-1-18-go-build-run-with-error-my-system-is-mac-12

In the meantime I've reverted the go update on the alpha branch until we can investigate/implement a fix.