added deprecation warnings to endreq and messageService()

This is meant to help the merge of !79 and !80.

Fixes GAUDI-1225 

See merge request !183

GaudiKernel/GaudiKernel/CommonMessaging.h

@@ -79,7 +79,9 @@ public:
   /** The standard message service.
    *  Returns a pointer to the standard message service.
    *  (Alias to msgSvc())
+   *  \deprecated Will be removed in v28r1, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/80
    */
+  [[deprecated("will be removed in v28r1, use msgSvc() instead, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/80")]]
   inline SmartIF<IMessageSvc>& messageService() const {
     return msgSvc();
   }

GaudiKernel/GaudiKernel/Converter.h

@@ -110,7 +110,8 @@ protected:
   SmartIF<ISvcLocator>& serviceLocator() const;
   /// Retrieve pointer to message service
   SmartIF<IMessageSvc>& msgSvc() const;
-  // Obsoleted name, kept due to the backwards compatibility
+  /// \deprecated Use msgSvc() instead. Will be removed in v28r1, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/80
+  [[deprecated("will be removed in v28r1, use msgSvc() instead, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/80")]]
   SmartIF<IMessageSvc>& messageService() const;
   /// Get Data Manager service
   SmartIF<IDataManagerSvc>& dataManager() const;

GaudiKernel/GaudiKernel/MsgStream.h

@@ -245,8 +245,11 @@ inline MsgStream& endmsg(MsgStream& s) {
   return s.doOutput();
 }
 #if defined(GAUDI_V20_COMPAT) && !defined(G21_NO_ENDREQ)
-/// Macro provided for backward compatibility
-#define endreq endmsg
+/// \deprecated Provided for backward compatibility. User endmsg instead. Will be removed in v28r1, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/79
+[[deprecated("will be removed in v28r1, use endmsg instead, see https://gitlab.cern.ch/gaudi/Gaudi/merge_requests/79")]]
+inline MsgStream& endreq(MsgStream& s) {
+  return s.doOutput();
+}
 #endif
 
 /// MsgStream format utility "a la sprintf(...)"