syslog-ng: bump to 3.9.1 and fix typo

Likewise fix default configuration to use SOCK_DGRAM and not SOCK_STREAM
as we currently do.

Add sha256 digest.

Rather than have the users replace syslog-ng.conf (which lately is
changing fairly frequently) and have them miss an important fix or
improvement, instead have them localize /etc/custom-logs.conf and
ship that as an empty file.

Signed-off-by: Philip Prindeville <philipp@redfish-solutions.com>

admin/syslog-ng/files/syslog-ng.conf

@@ -1,4 +1,4 @@
-@version:3.8
+@version:3.9
 
 options {
 	chain_hostnames(no);
@@ -14,7 +14,7 @@ options {
 
 source src {
 	internal();
-	unix-stream("/dev/log");
+	unix-dgram("/dev/log");
 };
 
 source net {
@@ -35,3 +35,6 @@ log {
         source(kernel);
 	destination(messages);
 };
+
+@include "/etc/custom-logs.conf"
+