Add missing FindNode prototype to net.h

Also make the argument a const std::string & instead of pass-by-value.

src/net.cpp

@@ -456,7 +456,7 @@ CNode* FindNode(const CNetAddr& ip)
     return NULL;
 }
 
-CNode* FindNode(std::string addrName)
+CNode* FindNode(const std::string& addrName)
 {
     LOCK(cs_vNodes);
     BOOST_FOREACH(CNode* pnode, vNodes)

src/net.h

@@ -59,6 +59,7 @@ bool RecvLine(SOCKET hSocket, std::string& strLine);
 bool GetMyExternalIP(CNetAddr& ipRet);
 void AddressCurrentlyConnected(const CService& addr);
 CNode* FindNode(const CNetAddr& ip);
+CNode* FindNode(const std::string& addrName);
 CNode* FindNode(const CService& ip);
 CNode* ConnectNode(CAddress addrConnect, const char *pszDest = NULL);
 bool OpenNetworkConnection(const CAddress& addrConnect, CSemaphoreGrant *grantOutbound = NULL, const char *strDest = NULL, bool fOneShot = false);