debug: Add version number to debug log

src/cmds/restic/main.go

@@ -9,6 +9,7 @@ import (
 	"restic"
 	"restic/debug"
 	"restic/options"
+	"runtime"
 
 	"github.com/spf13/cobra"
 
@@ -57,6 +58,8 @@ func init() {
 
 func main() {
 	debug.Log("main %#v", os.Args)
+	debug.Log("restic %s, compiled with %v on %v/%v",
+		version, runtime.Version(), runtime.GOOS, runtime.GOARCH)
 	err := cmdRoot.Execute()
 
 	switch {