Make sure system_clock uses high-resolution timer
Make sure system_clock uses high-resolution timer

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