filedesc: oops.. commit missing change to filedesc.h
Lock iir(4) and mark it MPSAFE.
- Add a per-device mutex to the softc and use it for bus_dma tags,
  CAM SIMs, callouts, and interrupt handler.
- Switch from timeout(9) to callout(9).
- Add a separate global mutex to protect the global event buffer ring.
- Return completed index from iir_intr_locked() and remove the global
  gdt_wait_* variables.
- Remove global list of gdt softcs and replace its use with
  devclass_get_device().
- Use si_drv1 to store softc pointer in the SDEV_PER_HBA case instead
  of minor numbers.
- Do math on osreldate instead of dubious char math on osrelease[]
  that didn't work on 10.0+.
- Use bus_*() instead of bus_space_*().
- Use device_printf() instead of printf() with a unit number.

Tested by:	no one
- Use the existing driver lock in cdevsw methods and remove D_NEEDGIANT.
- Use callout(9) instead of timeout(9).
- Use bus_*() instead of bus_space_*().
- Don't check for a NULL softc in attach.

Tested by:	no one
Extend earlier addition of stack frames to most of support.S.  This makes
stack traces in KDB, HWPMC, and DTrace much more reliable and useful.

Reviewed by:	kan, kib
Obtained from:	Netflix, Inc.
MFC after:	5 days