Removed unused variables in write_xml_primitives.f90.
Removed unused variables in write_xml_primitives.f90.

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