Fix #426 crash because race of 'success' flag on connection

src/searchdha.cpp

@@ -2192,7 +2192,7 @@ void AgentConn_t::StartRemoteLoopTry ()
		m_tOutput.Reset ();
		InitReplyBuf ();
		m_bConnectHandshake = true;
		m_bSuccess = false;
		m_bSuccess = 0;
		m_iStartQuery = 0;
		m_pPollerTask = nullptr;

@@ -2507,12 +2507,12 @@ bool AgentConn_t::CommitResult ()
		return BadResult ();

	Finish();
	m_bSuccess = true;

	if ( !bWarnings )
		bWarnings = m_dResults.FindFirst ( [] ( const CSphQueryResult &dRes ) { return !dRes.m_sWarning.IsEmpty(); } );

	agent_stats_inc ( *this, bWarnings ? eNetworkCritical : eNetworkNonCritical );
	m_bSuccess = 1;
	return true;
}

src/searchdha.h

@@ -481,7 +481,7 @@ struct AgentConn_t : public ISphRefcountedMT

	CSphRefcountedPtr<IReporter_t>	m_pReporter { nullptr };	///< used to report back when we're finished
	LPKEY			m_pPollerTask = nullptr; ///< internal for poller. fixme! privatize?
	bool			m_bSuccess = false;		///< agent got processed, no need to retry
	CSphAtomic		m_bSuccess;		///< agent got processed, no need to retry

public:
	AgentConn_t () = default;