mount: fix "mount_fusefs: -o timeout=: option not supported" on FreeBSD

Before this change `rclone mount` would give this error on FreeBSD

    mount helper error: mount_fusefs: -o timeout=: option not supported

Because the default value for FreeBSD was set to 15m for
--daemon-timeout and that FreeBSD does not support the timeout option.

This change sets the default for --daemon-timeout to 0 on FreeBSD
which fixes the problem.

Fixes #3610

cmd/mountlib/mount.go

@@ -39,8 +39,8 @@ var (
 )
 
 func init() {
-	// DaemonTimeout defaults to non zero for macOS and freebsd
-	if runtime.GOOS == "darwin" || runtime.GOOS == "freebsd" {
+	// DaemonTimeout defaults to non zero for macOS
+	if runtime.GOOS == "darwin" {
 		DaemonTimeout = 15 * time.Minute
 	}
 }