exclude cmfd cases when not compiling with PETSc
exclude cmfd cases when not compiling with PETSc

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