protect MPI library version detection from incompatible MPI libraries

  if (flags & COMM) {

    int major,minor,len;

#if (defined(MPI_VERSION) && (MPI_VERSION > 2)) || defined(MPI_STUBS)

    char version[MPI_MAX_LIBRARY_VERSION_STRING];

    MPI_Get_library_version(version,&len);

#else

    char version[] = "Undetected MPI implementation";

    len = strlen(version);

#endif

    MPI_Get_version(&major,&minor);

    MPI_Get_library_version(version,&len);

    if (len > 80) {

      char *ptr = strchr(version+80,'\n');

      if (ptr) *ptr = '\0';