Fix descriptors leak.

PR:		bin/191002
Reported by:	Ryan Steinmetz
Submitted by:	mjg


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271577 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Remove the limit on descriptors that can be send in one nvlist.

Submitted by:	Mariusz Zaborski


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271578 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f
Use non-recursive algorithm for traversing nvlists. This also removes
the limit on number of nested nvlists.

Submitted by:	Mariusz Zaborski


git-svn-id: svn+ssh://svn.freebsd.org/base/head@271579 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f