Don't clear out transient addressmap entries on HUP

If you really want to purge the client DNS cache, the TrackHostExits
mappings, and the virtual address mappings, you should be using NEWNYM
instead.

Fixes bug 1345; bugfix on Tor 0.1.0.1-rc.

Note that this needs more work: now that we aren't nuking the
transient addressmap entries on HUP, we need to make sure that
configuration changes to VirtualAddressMap and TrackHostExits actually
have a reasonable effect.

changes/bug1345

@@ -0,0 +1,4 @@
+  o Minor bugfixes:
+    - On SIGHUP, do not clear out all TrackExitHost mappings, client DNS
+      cache entries, and virtual address mappings: that's what NEWNYM is
+      for.  Bugfix on Tor 0.1.0.1-rc; fixes bug 1345.

src/or/main.c

@@ -1417,7 +1417,6 @@ do_hup(void)
 
   router_reset_warnings();
   routerlist_reset_warnings();
-  addressmap_clear_transient();
   /* first, reload config variables, in case they've changed */
   if (options->ReloadTorrcOnSIGHUP) {
     /* no need to provide argc/v, they've been cached in init_from_config */