Only set the syncbase --host arm-apple-darwin when building for arm devices, and not amd64 devices.
Only set the syncbase --host arm-apple-darwin when building for arm
devices, and not amd64 devices.

Change-Id: Id3bc27840f7b1f299426ea594115220f9ee5f895

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools