[Xorg-driver-geode] Allocate the Video overlay memory (use exaOffscreenAlloc) issue

[Cui, Hunk]

Hi, all

	The video overlay memory (use exaOffscreenAlloc mechanism)
(xf86-video-geode -> lx_video.c -> LXAllocMem), replaced the
GeodeAllocOffscreen, let it get the memory allocation under
exaOffscreenAlloc, then just allowing larger sizes might be a side
effect. It can achieve the dynamic distribution.

	I have been modified it (use exaOffscreenAlloc in LXAllocMem)
and it can normally work. 

	But another part is LXAllocateSurface & LXFreeSurface function,
they also use GeodeAllocOffscreen & GeodeFreeOffscreen, I can't find how
to trigger it, Alex gave me some suggestion: 'xawtv' tools used to use
it. It might have only used it in conjunction with the old v4l ddx. Only
know xawtv is a television viewer-X11 application. If anyone known about
this info, please tell me the methods.

	I think the Video overlay memory (use exaOffscreenAlloc) patches
will be committed after release the 2.11.9, please be patience to wait.
Any other questions, feel free to report.

Thanks,
Hunk Cui