MFC r296530: MFV r296529:

MFC r296530: MFV r296529:
6672 arc_reclaim_thread() should use gethrtime() instead of ddi_get_lbolt()
6673 want a macro to convert seconds to nanoseconds and vice-versa

Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Prakash Surya <prakash.surya@delphix.com>
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: Dan McDonald <danmcd@omniti.com>
Author: Eli Rosenthal <eli.rosenthal@delphix.com>

illumos/illumos-gate@a8f6344fa0921599e1f4511e41b5f9a25c38c0f9

git-svn-id: svn://svn.freebsd.org/base/stable/10@297116 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f