Don't create Legendre polynomial object unless actually needed
Don't create Legendre polynomial object unless actually needed

walshjon/openmc,wbinventor/openmc,liangjg/openmc,mit-crpg/openmc,paulromano/openmc,walshjon/openmc,amandalund/openmc,amandalund/openmc,mit-crpg/openmc,mit-crpg/openmc,paulromano/openmc,wbinventor/openmc,smharper/openmc,mit-crpg/openmc,smharper/openmc,wbinventor/openmc,liangjg/openmc,liangjg/openmc,shikhar413/openmc,walshjon/openmc,amandalund/openmc,smharper/openmc,smharper/openmc,shikhar413/openmc,liangjg/openmc,paulromano/openmc,shikhar413/openmc,amandalund/openmc,walshjon/openmc,shikhar413/openmc,wbinventor/openmc,paulromano/openmc