Signature:

      SUBROUTINE h5pget_fill_value_f(prp_id, type_id, fillvalue, hdferr)
        INTEGER(HID_T), INTENT(IN)  :: prp_id
        INTEGER(HID_T), INTENT(IN)  :: type_id
        TYPE(C_PTR)   , INTENT(OUT) :: fillvalue
        INTEGER       , INTENT(OUT) :: hdferr

Inputs:

      prp_id    - Property list identifier
      type_id   - Datatype identifier of fill value datatype (in memory)

Outputs:

      fillvalue - Fillvalue
      hdferr    - Returns 0 if successful and -1 if fails