Fix restoring the file context of the user's tty with SELinux.

Also fix broken tty labeling when running a command in a pty.
Includes a fix for a typo introduced in the last change set.

src/sudo.h

@@ -171,6 +171,7 @@ struct command_details {
     const char *selinux_role;
     const char *selinux_type;
     const char *utmp_user;
+    const char *tty;
     char **argv;
     char **envp;
 #ifdef HAVE_PRIV_SET