cmake MFEM examples

LLNL/axom src/cmake/thirdparty/FindMFEM.cmake :29

find_package(MFEM CONFIG QUIET NO_DEFAULT_PATH ${_mfem_required} HINTS
             ${MFEM_DIR}/cmake/mfem 
             ${MFEM_DIR}/lib/cmake/mfem
             ${MFEM_DIR}/share/cmake/mfem
             ${MFEM_DIR}/share/mfem
             ${MFEM_DIR}/mfem)