Port the SiS DRM to FreeBSD. This includes the ability for the DRM to

    allocate framebuffer memory without sisfb, and a new ioctl to be used
    by the X Server which tells the DRM what region of framebuffer memory
    to allocate from. Also fixes a possibility to panic the kernel I
    believe. Tested on linux with sisfb and FreeBSD (without sisfb) with
    new DRI only.