Hi everyone,

This week, I set up my testing suite with sdl2 because sdl3 has been a little complicated
with GitHub actions. I realized I needed to fix symbol duplications and macros that point to function returns.

I finally fixed symbol duplications in DMD. I realized DMD was already trying to handle that by marking duplicates as extern variables but it wasn't handling it well.

I had to ensure that

int a;
int a;
int a;

becomes

int a;
extern int a;
extern int a;

so we get only one symbol emitted in object file and that works without any complications.

Link to PR: https://github.com/dlang/dmd/pull/22003/commits/158e2455c3a0befd9ddb8d8e8906a421969cdf52