make-snapshot: fix circular dependency

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@57070 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

tool/make-snapshot

@@ -329,6 +329,7 @@ def package(vcs, rev, destdir, tmp = nil)
         "BOOTSTRAPRUBY"=>baseruby,
         "PWD"=>Dir.pwd,
         "CONFIGURE"=>"configure",
+        "arch"=>"noarch",
       }
       vars["UNICODE_VERSION"] = $unicode_version if $unicode_version
       args = vars.dup