message: Suppress "extra semi-colon" warnings from "sidre.hpp" when the macro
  MFEM_HAVE_GCC_PRAGMA_DIAGNOSTIC is defined.
diff: #ifdef MFEM_USE_SIDRE
  #include "datacollection.hpp"
  +#ifdef MFEM_HAVE_GCC_PRAGMA_DIAGNOSTIC
  +# pragma GCC diagnostic push
  +# if defined(__clang__)
  +# pragma GCC diagnostic ignored "-Wextra-semi"
  +# else // real GCC?
  +# pragma GCC diagnostic ignored "-Wpedantic"
  +# endif
  +#endif
  #include <sidre/sidre.hpp>
  +#ifdef MFEM_HAVE_GCC_PRAGMA_DIAGNOSTIC
  +# pragma GCC diagnostic pop
  +#endif
  namespace mfem
  {
  