Use StoredDeclsList::HandleRedeclaration instead of home-grown.
Use StoredDeclsList::HandleRedeclaration instead of home-grown.

llvm upgrade; might need to revisit for unload failures.

marsupial/cling,karies/cling,root-mirror/cling,root-mirror/cling,marsupial/cling,karies/cling,root-mirror/cling,marsupial/cling,karies/cling,karies/cling,karies/cling,root-mirror/cling,marsupial/cling,root-mirror/cling,karies/cling,marsupial/cling,marsupial/cling,root-mirror/cling