Updated gdmd/gdc man pages

[Johan Granberg]

Anders F Björklund wrote:
> I did include the -I flag, only because -I and -J
> are very similar and thus potentially confusing...
> (one might want to include some other common options,
> like for instance the usual GCC -c, -o or -g  flags?)

I think this would be a good idea. If we added the most common options and
equivalents to dmds options where available it would be an improvement.

> PS. The gcc man page is like 5,000 or 10,000 lines.
> So we do not want to copy all of it over to gdc. :-)

I agree with that reading gcc manpage is an adventure in itself :D