BUG: globalMeshData() : trigger of globalMeshData inside e.g. deltaCoeffs

Original fix (http://www.openfoam.org/mantisbt/view.php?id=1780)
did an increment to create a new communicator. This might
access the communicator-to-mpi_structure tables in PstreamGlobals.H outside
range. Instead allocate and release communicator.