MFC: r259428

Clear content of keyfiles loaded by the loader after processing them.

MFC: r259429

Clear some more places with potentially sensitive data.
MFC r264096, r264097, r264099 r264100, r264101, r264102, r264119:

Fixes to the ti_sdhci and sdhci drivers (fix clock divisor calcs).

Use the ti_sdhci driver instead of ti_mmchs for Pandaboard.
MFC 266621: Eliminte spurious interrupts caused by ARM weak memory ordering.
MFC r266520:

Explicitly link libzfs against libavl as it is done in OpenSolaris
(4543:12bb2876a62e).  Without this, some third party applications
may break because the lack of AVL related symbols.

FreeBSD base system are not affected because the FreeBSD ZFS command
line tools were all linked against libavl and thus hide the underlying
issue.

PR:	bin/183081
Merge remote-tracking branch 'freebsd/stable/10' into hardened/10/aslr