MFC r271137:
Add mrsas(4) to GENERIC for i386 and amd64.

Approved by:	re (gjb)
MFC r262351:

    Remove KASSERT from in6p_lookup_mcast_ifp().

    When the devel/jenkins port, version 1.551 was started,
    the kernel would panic if INVARIANTS was enabled in the kernel config.

    Suggested by: bms

Approved by: re (gjb)
MFC r256956:
Improve ZFS N-way mirror read performance by using load and locality
information.

MFC r260713:
Fix ZFS mirror code for handling multiple DVA's

Also make the addition of the d_rotation_rate binary compatible. This allows
storage drivers compiled for 10.0 to work by preserving the ABI for disks.

Approved by:	re (gjb)
Sponsored by:	Multiplay
Fix previous commit: unbreak build of libkvm by including sys/systm.h
only when _KERNEL is defined.

Approved by:	re@ (implicit)