Fix compile warning when compiling with GCC.

MFC after:	3 days
Sponsored by:	Mellanox Technologies
Our packet filters use mbuf's rcvif pointer to determine incoming interface.
Change mbuf's rcvif to enc0 and restore it after pfil processing.

PR:		110959
Sponsored by:	Yandex LLC
make userland __assfail from opensolaris compat honor 'aok' variable

This should allow zdb -A option to actually make difference.

MFC after:	2 weeks
reduce L2ARC_WRITE_SIZE on FreeBSD

FreeBSD has ARC_BUFC_NUMMETADATALISTS metadata lists and ARC_BUFC_NUMDATALISTS
data lists (currently both are 16) while illumos has just a single list
of each kind.

L2ARC_WRITE_SIZE determines the default value of l2arc_write_max which
defines limits on how much data is scanned and written to a cache device
during each run of the l2arc feed thread.  The limits are applied on the
per buffer list basis.
Because FreeBSD has more lists we proportionally reduce the limits.

Reviewed by:	Brendan Gregg (earlier version)
MFC after:	2 weeks
Sponsored by:	HybridCluster
Fix a bug introduced in
https://svnweb.freebsd.org/base?view=revision&revision=272347

MFC after: 3 days
Merge remote-tracking branch 'freebsd/master' into hardened/current/master
Merge remote-tracking branch 'origin/hardened/current/master' into hardened/current/userlandenhanced