Automatically enable some hdparm tweaks to CD burners

On some CD burners (mine), the buffer will not stay full without a few hdparm
tweaks. The result of a buffer underrun with BURNFREE is that the drive slows
down, but reports that the burn succeeded; in reality, the burned CD can be
invalid. I have had a case where a drive "possibly" buffer underran 11 times
burning an Ubuntu install CD, which wouldn't verify. After trying burning at
rediculously low speeds, I eventually fixed it by tweaking the hdparm settings.

The settings needed are "-u1 -c1", for unmasking other interrupts and doing true
32 bit asynchronous IO. By setting these for a CD burner, access speed is
increased to allow burning at 48x or higher without the drive's internal buffer
ever being under 98% full.

Note that I was burning from an ISO image stored on a SATA hard drive, and the
drive is a newer DVDDL+-RW drive on an ATA133 bus and cable, all by itself.
There are no bus speed issues here. I also did not enable DMA.