Use runtime info to determine ARM version for upgrade (fixes #1051)

internal/upgrade/releasename_darwin.go

@@ -0,0 +1,25 @@
+// Copyright (C) 2014 The Syncthing Authors.
+//
+// This program is free software: you can redistribute it and/or modify it
+// under the terms of the GNU General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
+// more details.
+//
+// You should have received a copy of the GNU General Public License along
+// with this program. If not, see <http://www.gnu.org/licenses/>.
+
+package upgrade
+
+import (
+	"fmt"
+	"runtime"
+)
+
+func releaseName(tag string) string {
+	return fmt.Sprintf("syncthing-macosx-%s-%s.", runtime.GOARCH, tag)
+}