__dirname value differs from tsc and tsx

When I call ```__dirname``` in tsc or tsx its value is the current directory. But in tsup the value is the entrypoint directory.

Example:

Suppose there is a project where the entry point is /home/project/src/server/index.ts:
```ts
import '../modules/example'
```

And the file /home/project/src/modules/example.ts:
```
console.log(__dirname)
```

When I build from tsc or run using tsx, the result is:
```
/home/project/dist/modules/
```

But when I build from tsup the result is:
```
/home/project/dist/server
```

Is there a way to get same result from tsc and tsx?

Reproduce the example with the entrypoint /home/project/src/server/index.ts and imported file /home/project/src/modules/example.ts, comparing tsup with tsc and tsx. Read how tsup handles __dirname during the build; done means determining whether the output can match the other tools and documenting or addressing the discrepancy.

Written by the indexing model from the issue text.