Fixed missing include for libmesh-v1.3.1 compatibility in struct ex 7.
Fixed missing include for libmesh-v1.3.1 compatibility in struct ex 7.


MASTmultiphysics/mast-multiphysics,MASTmultiphysics/mast-multiphysics,MASTmultiphysics/mast-multiphysics,MASTmultiphysics/mast-multiphysics