drm: Fix conditionals around drmkms_pci and agp.

Kernel should build now with all pci drm drivers stripped out but
DRM_LEGACY still enabled. (Might not be very useful, but it'll
build. Maybe we should also have DRM_LEGACY_PCI so those drivers can
be modloaded later.)

branches: 1.17.4;
drm: Propagate CPPFLAGS.drmkms into all the drm drivers.

drm/vmwgfx: First draft. Passes make depend, doesn't build yet.

Revert part of previous: no separate CPPFLAGS.drmkms.

There are too many drms users outside sys/external/bsd/drm2 for now;
will hold off on this until we find a better way to keep the drm
includes modularized.

Narrow the CPPFLAGS for drm subsystems.

No need for the whole kernel to be built with -I flags for the drm
header files.

Rework PCI and AGP conditionalization.

- Push drm_pci_set_unique into driver callback.
- Eliminate drm_pci_set_unique_hook.
- Gather all drm_agp_* functions into struct drm_agp_hooks.
- Replace the nonsensical old atomic garbage by serious locking.
- Make drm_agpsupport.c its own module.
- Eliminate NDRMKMS_PCI.
- Use NAGP from "agp.h" only in drm_module.c for horrible hack.
=> See comment in file for rationale.
- Always define CONFIG_PCI=1 and CONFIG_AGP=1.
- Always go through the drm_agp_* function hooks.
- Ifdef out nouveau agp stuff that doesn't go through drm_agp_*
for reasons that I'm too frustrated to figure out tonight.
- pci_iomap no longer automagically does agp_i810_borrow.
=> Use drm_agp_borrow instead.

Make drmkms build without drmkms_pci.

Sprinkle AGP conditionals where needed.

Add some amdgpu goo.

Upstream nixed __OS_HAS_AGP; use CONFIG_AGP instead.

branches: 1.8.16; 1.8.18;
Hook up viadrmums and include it it i386/ALL.

Just use `drm' for DRM/UMS PCI attachments at PCI devices.

It'll make life simpler. No need to distinguish drm from drm2 here
because it's just an interface attribute, no content, and we use it
compatibly: parent provides pci_attach_args.

Make viadrm (UMS) almost build.

Missing part: something needs to issue config_found_ia("drmums_pci"),
and config(5) needs to be told that it will do that. The sensible
approach is for vga_pci to do so. But config(5) doesn't seem to
understand that *only* vga_pci will do that, not all vga.

The old scheme was to tell config(5) that vga would always attach
drm, and actually attach it in vga_pci, and hope that nobody would
ever consider trying to attach non-PCI devices but quietly leave the
token `pci' out of the name of the drm interface attribute so it
didn't look wrong to have it outside dev/pci/files.pci.

Maybe that's still the right thing, as far as anything UMS can be
right.

Factor generic parts of intelfb out into a drmfb.

Adapting radeondrmkmsfb should not be hard.

This will make nouveaufb easier too.

branches: 1.4.2; 1.4.4; 1.4.6;
Add files.nouveau to files.drmkms_pci.

First whack at radeon driver.

No hardware to test yet, but it builds.

branches: 1.2.2; 1.2.4; 1.2.6;
Merge riastradh-drm2 to HEAD.

branches: 1.1.2;
file files.drmkms_pci was initially added on branch riastradh-drm2.