Win32 Error descriptions + config

Hello!

I'm at the win32 error messages once more.
The DLL load thingy doesn't work on all win9x machines, so i made it go thru a lookup table instead, using the DLL as last resort.
I also moved this out of the fe-misc.c file because of the size of the lookup table.
Who knows, we might add more other win32 specific code there in the future.

I also fixed a small typo in the pg_config.h.win32 that made the compiler complain about the gnu snprintf declaration.

I tried to make this patch with psql coding style.
I've successfully tested this on win2k and win98 and it works fine (i.e. the message shows on win98 too, it didn't with the old implementation).

Let me know if there's anything you want me to change or if you won't accept the patch for any reason.

Regards

Magnus Naeslund

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Programmer/Networker [|] Magnus Naeslund
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