banlist: log post-swept banlist size at startup

We are currently logging the size of the banlist before SweepBanned()
has been called, meaning the value may be incorrect.

src/banman.cpp

@@ -26,7 +26,7 @@ BanMan::BanMan(fs::path ban_file, CClientUIInterface* client_interface, int64_t
         SweepBanned();            // sweep out unused entries
 
         LogPrint(BCLog::NET, "Loaded %d banned node ips/subnets from banlist.dat  %dms\n",
-            banmap.size(), GetTimeMillis() - n_start);
+            m_banned.size(), GetTimeMillis() - n_start);
     } else {
         LogPrintf("Invalid or missing banlist.dat; recreating\n");
         SetBannedSetDirty(true); // force write