message: Support is_library_threadsafe() for older HDF5
diff: @@ -125,11 +125,18 @@ pub fn library_version() -> (u8, u8, u8) {
  /// Returns true if the HDF5 library is threadsafe.
  pub fn is_library_threadsafe() -> bool {
  + #[cfg(hdf5_1_8_16)]
  + {
  use self::internal_prelude::hbool_t;
  use hdf5_sys::h5::H5is_library_threadsafe;
  let mut ts: hbool_t = 0;
  h5call!(H5is_library_threadsafe(&mut ts)).map(|_| ts > 0).unwrap_or(false)
  }
  + #[cfg(not(hdf5_1_8_16))]
  + {
  + cfg!(h5_have_threadsafe)
  + }
  +}
  #[cfg(test)]
  pub mod tests {
  