Signature:
  SUBROUTINE h5pset_virtual_printf_gap_f(dapl_id, gap_size, hdferr)
    INTEGER(HID_T)  , INTENT(IN)  :: dapl_id
    INTEGER(HSIZE_T), INTENT(IN)  :: gap_size
    INTEGER         , INTENT(OUT) :: hdferr
Inputs:
  dapl_id  - Dataset access property list identifier for the virtual dataset.
  gap_size - Maximum number of files and/or datasets allowed to be missing 
             for determining the extent of an unlimited virtual dataset 
             with printf-style mappings.
Outputs:
  hdferr   - Returns 0 if successful and -1 if fails.