Finish porting libpciaccess

[kallisti5]

libpciaccess is required for libdrm_intel which is used for the old i915 3d-accelerated mesa renderer.

For now, we build drm with libdrm_intel disabled as i965 doesn't require it.

There is a partial port of libpciaccess in-tree which is pretty much the FreeBSD source code with freebsd renamed Haiku (and some other work). It also doesn't even compile the haiku_pci.c source code.

I began work on a real/functional haiku_pci.c before realizing that i915 is the only consumer of it (and we could skip it for now)

Attached is the partial work using Haiku's Poke driver to get raw PCI bus access from userspace.

The code populates the pci_sys struct with the current PCI devices attached to the system. Not implemented is raw access to the individual devices, memory mapping, etc.

Output of scanpci showing the initial device discovery code working is attached as well.

[kallisti5]

libpciaccess-haiku.zip