MT#59962 AmSession: remove unused func `onFailure()`

It's not used, just remove it.

Change-Id: I17d1241f2bd30ba123c22eb49851ea2a384fe898

core/AmSession.cpp

@@ -1296,34 +1296,6 @@ void AmSession::setOnHold(bool hold)
   unlockAudio();
 }
 
-void AmSession::onFailure()
-{
-  // switch (cause) {
-  //   case FAIL_REL100_421:
-  //   case FAIL_REL100_420:
-  //     if (rpl) {
-  //       dlg.cancel();
-  //       if (dlg.getStatus() < AmSipDialog::Connected)
-  //         setStopped();
-  //     } else if (req) {
-  //       if (cause == FAIL_REL100_421) {
-  //         dlg.reply(*req, 421, SIP_REPLY_EXTENSION_REQUIRED, NULL,
-  //             SIP_HDR_COLSP(SIP_HDR_REQUIRE) SIP_EXT_100REL CRLF);
-  //       } else {
-  //         dlg.reply(*req, 420, SIP_REPLY_BAD_EXTENSION, NULL,
-  //             SIP_HDR_COLSP(SIP_HDR_UNSUPPORTED) SIP_EXT_100REL CRLF);
-  //       }
-  //       /* finally, stop session if running */
-  //       if (dlg.getStatus() < AmSipDialog::Connected)
-  //         setStopped();
-  //     }
-  //     break;
-  //   default:
-  //     break;
-  // }
-}
-
-
 int AmSession::getRtpInterface()
 {
   if(rtp_interface < 0){

core/AmSession.h

@@ -571,8 +571,6 @@ public:
   /** answer for a locally sent PRACK is received */
   virtual void onPrack2xx(const AmSipReply &);
 
-  virtual void onFailure();
-
   virtual void onNoAck(unsigned int cseq);
   virtual void onNoPrack(const AmSipRequest &req, const AmSipReply &rpl);