Add dynamic symbol for _XGetRequest, which libX11 1.4.99.1 added.

Fixes Bugzilla #1376.
Hi Sam

In X11_CreateYUVOverlay hwdata->image will be accessed after it has been
freed, causing undefined behavior. Exchanging two lines as shown in this
patch will fix that problem:

Regards, Bodo
Backport from 1.3 branch: clean up opened joysticks in SDL_JoystickQuit().
Merged SDL 1.3 revision 5424, fixing a crash in the joystick code on recent kernels.