launcher: Add back support for specifying VT to run on

This is only available when running weston directly as root typically for
ssh logins.  It's a somewhat destructive option, as it will take over any
existing VT completely, unless there's already an display server running
there.

https://bugs.freedesktop.org/show_bug.cgi?id=69731
diff --git a/src/compositor-fbdev.c b/src/compositor-fbdev.c
index f0625cd..92aefda 100644
--- a/src/compositor-fbdev.c
+++ b/src/compositor-fbdev.c
@@ -880,7 +880,8 @@
 		goto out_free;
 
 	/* Check if we run fbdev-backend using weston-launch */
-	compositor->base.launcher = weston_launcher_connect(&compositor->base);
+	compositor->base.launcher =
+		weston_launcher_connect(&compositor->base, param->tty);
 	if (compositor->base.launcher == NULL && geteuid() != 0) {
 		weston_log("fatal: fbdev backend should be run "
 			   "using weston-launch binary or as root\n");
@@ -897,7 +898,8 @@
 	compositor->session_listener.notify = session_notify;
 	wl_signal_add(&compositor->base.session_signal,
 		      &compositor->session_listener);
-	compositor->base.launcher = weston_launcher_connect(&compositor->base);
+	compositor->base.launcher =
+		weston_launcher_connect(&compositor->base, param->tty);
 	if (!compositor->base.launcher) {
 		weston_log("Failed to set up launcher.\n");
 		goto out_udev;