cam: Add a XPORT_NVMF for NVMe over Fabrics sims

[jhb]

Summary

Sponsored by: Chelsio Communications

[imp]

Looks good. Two minor nits to consider

sbin/camcontrol/camcontrol.c

5282

Can this be a table lookup instead?

5425

switch statements?

[jhb]

sbin/camcontrol/camcontrol.c

5282

I wonder actually if I should just move this function to libnvmf. nvmecontrol has a duplicate copy already. I'm sure the compiler compiles it down to a jump table that is stored as a lookup table already in practice.

5425

The surrounding code here is all using if statements so I matched it.

Actually, though the rest of the function does transport first and then protocol, so I should maybe match that. I do wonder how much it matters to keep WITH_NVME here vs just always compiling these bits into camcontrol at this point.

[ken]

sbin/camcontrol/camcontrol.c

5425

I think we could probably just get rid of WITH_NVME at this point.

[imp]

sbin/camcontrol/camcontrol.c

5425

I think so too. nda hasn't been experimental for at least 5 years.
Not sure how that interacts with the rest of the build system, though I'm not entirely sure I care: We don't have WITHOUT_ATA or WITHOUT_SCSI

[jhb]

sbin/camcontrol/camcontrol.c

5425

Today MK_NVME controls this in part because nvmecontrol doesn't build on all platforms, but Warner has a review to fix nvmecontrol, and once that is in I think we should remove MK_NVME and just build these bits unconditionally. I probably will wait for that to happen first before landing this and will fix these up to follow the sensible order instead.

[jhb]

Move nvmf_transport_type to libnvmf

[jhb]

Rebase for removal of WITH_NVME