ntp: security update, and use libcrypto

http://support.ntp.org/bin/view/Main/SecurityNotice#Recent_Vulnerabilities

The package would no longer build without libcrypto,
and it wouldn't find it without pkgconfig.
I checked that Debian and Arch do use openssl as a dependency,
so it's probably not so bad a thing to have.

CC maintainer @edolstra.

(cherry picked from commit 0fbc5ddadb47c704ce4e41792ce4d61d8ee1c9af)
ntp: Don't depend on openssl, don't install docs

(cherry picked from commit 782440310d69d239cc5480f97abf6a3a56a2840c)
Fix ntpd

Since the 4.2.8 upgrade, ntpd is broken on NixOS:

  Dec 28 19:06:54 hagbard ntpd[27723]: giving up resolving host 1.nixos.pool.ntp.org: Servname not supported for ai_socktype (-8)

This appears to be because DNS resolution doesn't work in chroots
anymore (due to /etc being missing). So disable chroots for now. It's
probably better to use systemd's containment facilities anyway.

(cherry picked from commit ea9d391bb5b1f8eb26e6fc0410de353a82e4220a)