Deterministic comments in the generated go files

```
// Code generated from /home/sustrik/.cache/bazel/_bazel_sustrik/329223ef44c790813be2d08fc6e228b5/sandbox/linux-sandbox/832/execroot/__main__/Foo.g4 by ANTLR 4.7.2. DO NOT EDIT.
```
Would it be possible to change that to:
```
// Code generated from Foo.g4 by ANTLR 4.7.2. DO NOT EDIT.
```
AFAICS this can be achieved by running the generator from the directory in question.