import/export: false positives for typescript overloads

Minimal example to reproduce (not a sensible use case for overloads, but anyway):

```
export function consume(val: number): void;
export function consume(val: string): void;
export function consume(val: number | string): void {
    // Do something.
}
```

All three `consume` will be annotated with ` error  Multiple exports of name 'consume'   import/export`.