Linux: Fix regfree being called on invalid data

This was caused by a careless merge that did not take the differences
between the branches into account.

Regression introduced by 7c7cc59889.

Fixes #2464

src/linux_joystick.c

@@ -334,8 +334,6 @@ void _glfwTerminateJoysticksLinux(void)
             closeJoystick(js);
     }
 
-    regfree(&_glfw.linjs.regex);
-
     if (_glfw.linjs.inotify > 0)
     {
         if (_glfw.linjs.watch > 0)