Added Mac arm64 config to allow test builds with M1.
Added Mac arm64 config to allow test builds with M1.

Change-Id: Ibb15af730efbb33d09660a952e1b8e36d6dd7a9e
Reviewed-on: http://review.couchbase.org/c/couchnode/+/154868
Reviewed-by: Sergey Avseyev
Tested-by: Brett Lawson <c8c4369773d7d7226e031f0c4af62e3f38a08510@gmail.com>

couchbase/couchnode,couchbase/couchnode,brett19/couchnode,brett19/couchnode,couchbase/couchnode,brett19/couchnode,couchbase/couchnode