Suppress "decided to publish new descriptor" message when not a server

The message only means that we're publishing a new descriptor when we
are actually in some kind of server mode, and publication is on.

Fix for bug 3942; bugfix on 0.2.3.2-alpha.

changes/bug3942

@@ -0,0 +1,4 @@
+  o Minor bugfixes:
+    - Don't log that we have "decided to publish new relay descriptor" unless
+      we are actually publishing a descriptor. Fix for bug 3942; bugfix on
+      0.2.3.2-alpha.

src/or/router.c

@@ -1738,8 +1738,10 @@ mark_my_descriptor_dirty_if_too_old(time_t now)
 void
 mark_my_descriptor_dirty(const char *reason)
 {
+  const or_options_t *options = get_options();
+  if (server_mode(options) && options->_PublishServerDescriptor)
+    log_info(LD_OR, "Decided to publish new relay descriptor: %s", reason);
   desc_clean_since = 0;
-  log_info(LD_OR, "Decided to publish new relay descriptor: %s", reason);
   if (!desc_dirty_reason)
     desc_dirty_reason = reason;
 }