This patch adds support for chronyd's stratumpweight both in the NTP
client (ietf-system) and client+server (ietf-ntp) should fix the flaky
NTP stratum test.
Also, make sure to *not* 'rm -rf /etc/chrony/conf.d/*' in system.c to
prevent clobbering settings potentially made in ntp.c
Signed-off-by: Joachim Wiberg <troglobit@gmail.com>