Allow link-time-optimization with GCC
Allow link-time-optimization with GCC

smharper/openmc,amandalund/openmc,shikhar413/openmc,bhermanmit/openmc,mit-crpg/openmc,shikhar413/openmc,amandalund/openmc,bhermanmit/openmc,amandalund/openmc,samuelshaner/openmc,shikhar413/openmc,walshjon/openmc,mit-crpg/openmc,wbinventor/openmc,liangjg/openmc,wbinventor/openmc,johnnyliu27/openmc,johnnyliu27/openmc,johnnyliu27/openmc,paulromano/openmc,mit-crpg/openmc,liangjg/openmc,samuelshaner/openmc,smharper/openmc,smharper/openmc,samuelshaner/openmc,smharper/openmc,paulromano/openmc,liangjg/openmc,johnnyliu27/openmc,wbinventor/openmc,amandalund/openmc,paulromano/openmc,walshjon/openmc,samuelshaner/openmc,shikhar413/openmc,paulromano/openmc,mit-crpg/openmc,walshjon/openmc,walshjon/openmc,liangjg/openmc,wbinventor/openmc