Directly include <stack>
Directly include <stack>

We must have been getting this indirectly in default builds, but we were
failing to compile when turning off all our options.

jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,dschwen/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,libMesh/libmesh,libMesh/libmesh,libMesh/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,dschwen/libmesh,libMesh/libmesh,dschwen/libmesh,jwpeterson/libmesh,dschwen/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,dschwen/libmesh,libMesh/libmesh,jwpeterson/libmesh