FreeBSD/DragonFly patches for xf86-video-ati, xf86-input-mouse, and xf86-video-intel

[Matthew Rezny]

What's all that FREEBSD_USB define mess? That is significantly different than 
what is currently in FreeBSD ports. I concur with Peter Hutterer, the changes 
aren't OS specific. A few months ago I updated xf86-input-mouse and simplified 
some of the ifdef mess we had accumulated in patches. Please try the patches 
currently in ports as-is with PkgSrc. They should be good to go upstream.

Michel Dänzer had a good point about using xf86LoadKernelModule or drmOpen in 
xf86-video-ati. We should follow convention where possible in our patches.