Do not add random inbound peers to addrman. (#1593)

We should learn about new peers via address messages.

An inbound peer connecting to us tells us nothing about
 its ability to accept incoming connections from us, so
 we shouldn't assume that we can connect to it based on
 this.

The vast majority of nodes on the network do not accept
 incoming connections, adding them will only slow down
 the process of making a successful connection in the
 future.

Nodes which have configured themselves to not announce would prefer we
 not violate their privacy by announcing them in GETADDR responses.

src/net_processing.cpp

@@ -1231,12 +1231,6 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 pfrom->fGetAddr = true;
             }
             connman.MarkAddressGood(pfrom->addr);
-        } else {
-            if (((CNetAddr)pfrom->addr) == (CNetAddr)addrFrom)
-            {
-                connman.AddNewAddress(addrFrom, addrFrom);
-                connman.MarkAddressGood(addrFrom);
-            }
         }
 
         // Relay alerts