overlay.d/20platform-chrony: additional skip of platform chrony config

Typically we'd think the user would only pass in optional arguments
to chrony via OPTIONS in /etc/sysconfig/chronyd but we found a case
where a user was providing actual config directives. Let's also
exit early out of coreos-platform-chrony-config if /etc/sysconfig/chronyd
has been touched. If either /etc/chrony.conf or /etc/sysconfig/chronyd
has been touched we just consider the user to own the config and not
do anything special based on the platform.

Fixes coreos/fedora-coreos-tracker#1449

overlay.d/20platform-chrony/usr/libexec/coreos-platform-chrony-config

@@ -18,6 +18,10 @@ if ! cmp {/usr,}/etc/chrony.conf >/dev/null; then
     echo "$self: /etc/chrony.conf is modified; not changing the default"
     exit 0
 fi
+if ! cmp {/usr,}/etc/sysconfig/chronyd >/dev/null; then
+    echo "$self: /etc/sysconfig/chronyd is modified; not changing the default"
+    exit 0
+fi
 
 mkdir -p /run/coreos
 confpath=/run/coreos/platform-chrony.conf