fixed compile errors when using MPI I/O
fixed compile errors when using MPI I/O

johnnyliu27/openmc,mit-crpg/openmc,paulromano/openmc,smharper/openmc,shikhar413/openmc,walshjon/openmc,samuelshaner/openmc,bhermanmit/openmc,amandalund/openmc,samuelshaner/openmc,liangjg/openmc,smharper/openmc,wbinventor/openmc,walshjon/openmc,liangjg/openmc,wbinventor/openmc,bhermanmit/cdash,wbinventor/openmc,sxds/opemmc,lilulu/openmc,lilulu/openmc,paulromano/openmc,smharper/openmc,samuelshaner/openmc,shenqicang/openmc,mit-crpg/openmc,amandalund/openmc,mjlong/openmc,johnnyliu27/openmc,kellyrowland/openmc,johnnyliu27/openmc,mit-crpg/openmc,wbinventor/openmc,liangjg/openmc,amandalund/openmc,nhorelik/openmc,paulromano/openmc,sxds/opemmc,samuelshaner/openmc,kellyrowland/openmc,amandalund/openmc,smharper/openmc,bhermanmit/openmc,nhorelik/openmc,lilulu/openmc,liangjg/openmc,shikhar413/openmc,walshjon/openmc,shikhar413/openmc,paulromano/openmc,walshjon/openmc,shenqicang/openmc,mjlong/openmc,mit-crpg/openmc,johnnyliu27/openmc,shikhar413/openmc