MFC r253865: Fixes to RX_COPY optimization code allowing the removal of the rearm_queues
             routine used in local_timer.
    r253965: Correct the queue mask bit clearing in the link interrupt handler.

Approved by: re
When the igb driver is static there are cases when early interrupts occur,
resulting in a panic in refresh_mbufs, to prevent this add a check in the
interrupt handler for DRV_RUNNING.
MFC 253048,253423,253449,253653,253774,253785:
- Allow mlx4 devices to switch between Ethernet and Infiniband:
  - Fix sysfs attribute handling by using sysctl_handle_string() and
    properly handling trailing newlines in attribute values.
  - Remove check forbidding requests that would result in one port being
    set to Ethernet and the subsequent port being set to IB.
- Avoid trashing IP fragments by correctly managing hardware checksumming.
- Fix panics when downing or unloading the mlx4 driver.

PR:		kern/179999, kern/174213, kern/180430, kern/180791
MFC r253497:
Use the right name for the vm_map_find(9) flag to specify shared mapping.
MFC r253709:
The pmap_qenter() and pmap_qremove() perform TLB invalidation on its
own, no need to call pmap_invalidate_range() one more time.
MFC r253417:
Clear the vnode knotes before destroying vpollinfo.

MFC r253737:
Split the destruction into the helper destroy_vpollinfo_free(), and
call it when raced, instead of destroy_vpollinfo().
MFC r253328:
Create a proper stack frame for i386 version of bcopy().
MFC r253525:
Use the same union name on the left and right sides of the conversion.
MFC r253526:
Fix several warnings.
Fix crash in aio_pty_cleanup() by initializing the pointer before
dereferencing.
MFC r253352:
MFi386: add ddb "show sysregs" command.
MFC r253076: rc.d/zfs: pass -v option to zfs mount
MFC r253067: zfsboottest: sync with changes in zfs boot code
MFC r253068: zfsboottest.sh: remove checks for things that are not
strictly required
MFC r253605: zfsboottest: remove explicit -Werror
MFC r253072: amd64: use -mno-omit-leaf-frame-pointer in addition to
-fno-omit-frame-pointer
MFC r253601: newvers.sh: fix the fallback case of git-svn detection
MFC r253602: newvers.sh: add another git-svn fallback
MFC r253070: zfs: load zpool.cache after a root fs is mounted
MFC r253073: zfs: try to properly handle i/o errors in mappedread_sf
Revert the MFC of the r244237, done as r244806.  There are indeed bugs
in XEN pmap.  The revert hides a panic with the cost of non-working
vfork(2), which means more obscure misbehaviour in the usermode.
Revert is only done on the stable branch to maintain the consistent
erratic behaviour.

PR:	kern/180788