setfacl: add recursive functionality

setfacl: add recursive functionality

Add a -R option to setfacl to operate recursively on directories, along
with the accompanying flags -H, -L, and -P (whose behaviour mimics
chmod).

A patch was submitted with PR 155163, but this is a new implementation
based on comments raised in the Phabricator review for that patch
(review D9096).

PR:		155163
Submitted by:	Mitchell Horne <mhorne063@gmail.com>
Reviewed by:	jilles
MFC after:	2 weeks
Relnotes:	Yes
Sponsored by:	The FreeBSD Foundation
Differential Revision:	https://reviews.freebsd.org/D14934