[AD] DAllegro 'export' crap hopefully fixed

[torhus@xxxxxxxxxx]

Bad luck that tjaden (Peter Wang?) improved the fix.sh script just when 
I was working on this.  But I guess we both saw what Matthew L. was 
doing, and decided to do something about this annoyance.

The reason I haven't done this before is a) it requires a relatively new 
compiler version and b) it took me five hours of tedious work.  But now 
it's done.

Linking DAllegro apps statically with Allegro without using a script to 
remove 'export' should work now.  Just add -version=STATICLINK to the 
command line when compiling, and the 'export' keyword will not be 
included anywhere.

On other platforms than Windows, 'export' is never used, and STATICLINK 
has no effect.

This is interesting part of the code:

---
template _export(char[] def)
{
   static if (ADD_EXPORT)
      const char[] _export = "export " ~ def;
   else
      const char[] _export = def;
}
---

Used like this:
mixin(_export!("extern extern (C) cpu_family;"));

So it's really a poor man's preprocessor...  But at least the problem is 
now contained within the code itself.  Let's hope D gets a cleaner way 
of doing this in the future.

I'll try to actually test static linking if I get some time tomorrow.