reverted rev. 50283

prevented assoc_container_factory_class<Container> from instantiating Container when this type is an MPL placeholder expression

[SVN r50709]

libs/flyweight

@@ -1 +1 @@
-Subproject commit 512b17a3aad237af2990fe4044cefa129554e406
+Subproject commit 522370ccd4c7abdcb78cdf8685abf40af9261b76