Signature:

      SUBROUTINE h5pget_virtual_count_f(dcpl_id, count, hdferr)
        INTEGER(HID_T), INTENT(IN)   :: dcpl_id
        INTEGER(SIZE_T), INTENT(OUT) :: count
        INTEGER, INTENT(OUT)         :: hdferr

Inputs:

      dcpl_id - The identifier of the virtual dataset creation property list.

Outputs:

      count   - The number of mappings.
      hdferr  - Returns 0 if successful and -1 if fails