INT 7F - Alloy MW386 - READ RESTRICTED DIRECTORY ENTRY FOR GROUP
        AH = F3h
        AL = group number
        CX = entry number
        ES:DI -> 64-byte buffer
Return: CF clear if successful
            CX = next entry number
            buffer filled with 63-byte directory info and 1-byte group number
        CF set on error (no more matching entries)
Note:   like AH=F2h, but only returns directories belonging to the specified
          group