Remove call to list_size from add_grid_points.
Remove call to list_size from add_grid_points.

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