Directx cleanup

well, i installed another windows partition today so i could test
the compatability between directx 7 and directx 5

the good news is that simply switching the desired directx
interface for the audio and video has got everything running

the input and audio are only using directx5 interfaces anyways,
so no features are compromised there. the video is using all
directx5 interfaces as well, except for the gamma functions.
the gamma functions do some error checking that the running
directx version supports the correct interfaces, so they will
fail gracefully when running on directx5.

this is good news indeed, because now any windows configuration
should run on SDL without an error during initialization.

the change is to simply change the directx api version in

/* We need these defines to mark what version of DirectX API we use */

note that none of this was tested under directx8 in any way,
but if what i know is correct, it won’t be a problem.

hopefully this can be put into 1.1.7 before release :]