ByteStreamCnvSvcBase: Remove m_rawEventWrite.

Remove the RawEvent pointer from ByteStreamCnvSvcBase; moving it to
ByteStreamCnvSvc as part of thread-safety work.
ByteStreamCnvSvcBase then becomes an abstract class, so remove it
from the entries file.

Event/ByteStreamCnvSvcBase/ByteStreamCnvSvcBase/ByteStreamCnvSvcBase.h

 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #ifndef BYTESTREAMCNVSVCBASE_BYTESTREAMCNVSVCBASE_H
@@ -37,15 +37,10 @@ public:
    /// Checks whether an IOpaqueAddress is a GenericAddress
    virtual StatusCode updateServiceState(IOpaqueAddress* pAddress) override;
 
-   /// Implementation of IByteStreamEventAccess: Get RawEvent
-   virtual RawEventWrite* getRawEvent() override { return m_rawEventWrite; }
-
    /// Implementation of IIncidentListener: Handle for EndEvent incidence
    virtual void handle(const Incident&) override;
 
 protected: // data
-   RawEventWrite* m_rawEventWrite;
-
    std::vector<std::string> m_initCnvs;
    std::vector<std::string> m_ROD2ROBmap;
 };

Event/ByteStreamCnvSvcBase/src/ByteStreamCnvSvcBase.cxx

 /*
-  Copyright (C) 2002-2019 CERN for the benefit of the ATLAS collaboration
+  Copyright (C) 2002-2020 CERN for the benefit of the ATLAS collaboration
 */
 
 #include "ByteStreamCnvSvcBase/ByteStreamCnvSvcBase.h"
@@ -16,8 +16,8 @@
 
 //______________________________________________________________________________
 ByteStreamCnvSvcBase::ByteStreamCnvSvcBase(const std::string& name, ISvcLocator* pSvcLocator) :
-   ::AthCnvSvc(name, pSvcLocator, ByteStreamAddress::storageType()),
-	m_rawEventWrite(0) {
+   ::AthCnvSvc(name, pSvcLocator, ByteStreamAddress::storageType())
+{
    declareProperty("InitCnvs", m_initCnvs); 
    // This property is used by Tile BS converter, not by this class.
    declareProperty("ROD2ROBmap", m_ROD2ROBmap);

Event/ByteStreamCnvSvcBase/src/components/ByteStreamCnvSvcBase_entries.cxx

-#include "ByteStreamCnvSvcBase/ByteStreamCnvSvcBase.h"
 #include "ByteStreamCnvSvcBase/ByteStreamAddressProviderSvc.h"
 #include "ByteStreamCnvSvcBase/ROBDataProviderSvc.h"
 #include "../ROBDataProviderMTTest.h"
 
-DECLARE_COMPONENT( ByteStreamCnvSvcBase )
 DECLARE_COMPONENT( ByteStreamAddressProviderSvc )
 DECLARE_COMPONENT( ROBDataProviderSvc )
 DECLARE_COMPONENT( ROBDataProviderMTTest )