Merge branch 'thread.AtlasDetDescr-20190314' into 'master'

AtlasDetDescr: Enable thread-safety checker.

See merge request atlas/athena!21899

DetectorDescription/AtlasDetDescr/AtlasDetDescr/ATLAS_CHECK_THREAD_SAFETY

+DetectorDescription/AtlasDetDescr

DetectorDescription/AtlasDetDescr/AtlasDetDescr/AtlasDetectorID.h

@@ -314,10 +314,10 @@ protected:
 
     /// Flag for subclasses to know whether or not to perform
     /// checks. In general, this is set to false in optimized mode.
-    mutable bool        m_do_checks;
+    bool        m_do_checks;
     /// Flag for subclasses to know whether or not to perform
     /// neighbour initialization
-    mutable bool        m_do_neighbours;
+    bool        m_do_neighbours;
 
     /// pointer to the message service
     IMessageSvc*        m_msgSvc;