Revert "Add 381 to the buffer (You are now an IRC Operator)"

This reverts commit 11e5f7636d.

Having this in the raw buffer multiple times is obviously wrong, because you can
use /oper more than once and would get a new 381 numeric each time. So this
would need to use UpdateRawBuffer() instead of AddRawBuffer() (=replace old
entries with the same text).

However, this is still wrong. If you -o yourself, you no longer have oper
status. ZNC wouldn't notice this and still deliver the 381 numeric to new
clients.

Clients which use raw 381 to detect oper status will have to switch to user mode
+o.

Thanks to Han` for reporting this problem.

src/IRCSock.cpp

@@ -420,9 +420,6 @@ void CIRCSock::ReadLine(const CString& sData) {
 
 				break;
 			}
-			case 381:  // You are now an IRC Operator
-				m_pNetwork->AddRawBuffer(":" + _NAMEDFMT(sServer) + " " + sCmd + " {target} " + _NAMEDFMT(sRest));
-				break;
 			case 375:  // begin motd
 			case 422:  // MOTD File is missing
 				if (m_pNetwork->GetIRCServer().Equals(sServer)) {