CBLT-42:  set GOHOSTARCH=%GOARCH%

Change-Id: Iaa9d335b9219fbd32e8cee4e3ce1d0a7711f810c
Reviewed-on: http://review.couchbase.org/37109
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>