libpciaccess support for has_kernel_driver method

[matthew green <mrg%eterna.com.au@localhost>]

hi folks.


something really nasty happens on drmkms kernels if the "vesa" xorg
driver is loaded.  they're not compatible and won't become that way.

the way xf86-video-vesa handles this is by a libpciaccess call to
determine if the device has a kernel driver attached.  i've implemented
this below via 3 parts:

        - new pciio.h ioctl to get driver name

        - new libpci function to export this

        - new libpciaccess code for has_kernel_driver method.  this
          code explicitly ignores "vga" driver as being bound, but
          any other name will work.

each built on top of the other.  i've tested it both with drmkms
kernel and non-drmkms kernel, both with and without forcing vesa
driver to be used in xorg.conf, and it works as expected.

        http://www.netbsd.org/~mrg/vesa-blacklist.src.diff
        http://www.netbsd.org/~mrg/vesa-blacklist.xsrc.diff

comments?  i'd like to get this in ASAP.


.mrg.