xAODCoreCnv: Manually sweep missing pieces from 21.2 to master

Relates to ATLASRECTS-5632 : Missing DynVarFixerAlg. This is brought in as is in master from 21.2

Perhaps it relates also to ATLASRECTS-5631 : As ElementLinkResetAlg also seems to have been ahead 1-2 commit in 21.2 vis a vis master

Mentioning @akraszna and @jcatmore

Event/xAOD/xAODCoreCnv/src/components/xAODCoreCnv_entries.cxx

@@ -5,7 +5,10 @@
 #include "../AuxStoreWrapper.h"
 #include "../ElementLinkResetAlg.h"
 #include "../ROOTHeaderLoaderSvc.h"
+#include "../DynVarFixerAlg.h"
+
 
 DECLARE_COMPONENT( xAODMaker::AuxStoreWrapper )
 DECLARE_COMPONENT( xAODMaker::ElementLinkResetAlg )
 DECLARE_COMPONENT( xAODMaker::ROOTHeaderLoaderSvc )
+DECLARE_COMPONENT( xAODMaker::DynVarFixerAlg )