Add back DCWorkflowGraph.

This is just to fix compilation of very old ERP5 versions.
Do not merge into master!!

stack/erp5-zope2/buildout.cfg

@@ -679,6 +679,9 @@ eggs = ${neoppod:eggs}
   strict-rfc3339
   jsonschema[format]
 
+# For very old ERP5 versions
+  Products.DCWorkflowGraph
+
 entry-points =
   runwsgi=Products.ERP5.bin.zopewsgi:runwsgi
 scripts =
@@ -884,6 +887,9 @@ zope.event= 3.5.2
 zope.exceptions = 3.6.2
 zope.testing = 3.9.7
 
+# For very old ERP5 versions
+Products.DCWorkflowGraph = 0.4.1
+
 [ZODB]
 major = 4