MFC r289563,r291481,r292537,r292538,r292542,r292543,r292544 and r292834:

Update the LinuxKPI:
- Add more functions and types.
- Implement ACCESS_ONCE(), WRITE_ONCE() and READ_ONCE().
- Implement sleepable RCU mechanism using shared exclusive locks.
- Minor workqueue cleanup:
- Make some functions global instead of inline to ease debugging.
- Fix some minor style issues.
- In the zero delay case in queue_delayed_work() use the return value
from taskqueue_enqueue() instead of reading "ta_pending" unlocked and
also ensure the callout is stopped before proceeding.
- Implement drain_workqueue() function.
- Reduce memory consumption when allocating kobject strings in the
LinuxKPI. Compute string length before allocating memory instead of
using fixed size allocations. Make kobject_set_name_vargs() global
instead of inline to save some bytes when compiling.

Sponsored by: Mellanox Technologies

MFC r270710 and r270821:
- Update the OFED Linux Emulation layer as a preparation for a
hardware driver update from Mellanox Technologies.
- Remove empty files from the OFED Linux Emulation layer.
- Fix compile warnings related to printf() and the "%lld" and "%llx"
format specifiers.
- Add some missing 2-clause BSD copyrights.
- Add "Mellanox Technologies, Ltd." to list of copyright holders.
- Add some new compatibility files.
- Fix order of uninit in the mlx4ib module to avoid crash at unload
using the new module_exit_order() function.

Sponsored by: Mellanox Technologies

MFC r270710 and r270821:
- Update the OFED Linux Emulation layer as a preparation for a
hardware driver update from Mellanox Technologies.
- Remove empty files from the OFED Linux Emulation layer.
- Fix compile warnings related to printf() and the "%lld" and "%llx"
format specifiers.
- Add some missing 2-clause BSD copyrights.
- Add "Mellanox Technologies, Ltd." to list of copyright holders.
- Add some new compatibility files.
- Fix order of uninit in the mlx4ib module to avoid crash at unload
using the new module_exit_order() function.

Sponsored by: Mellanox Technologies