[tests] Don't fail duplicates check when running java tests
[tests] Don't fail duplicates check when running java tests

Summary:
`infer/tests/infer.make` unconditionally runs

```
$(call check_no_duplicates,$(INFER_OUT)/duplicates.txt)
```

as a part of `test` target. This requires the flag to be set to
produce `duplicates.txt`.

`clang.make` does this, but `java.make` was missing the flag which led
to an error on running `make tests` within
e.g. `tests/codetoanalyze/java/nullsafe-default`:

```
grep: infer-out/duplicates.txt: No such file or directory
```

Reviewed By: mityal

Differential Revision: D19373857

fbshipit-source-id: c2fcbe9dd

jvillard/infer,jvillard/infer,jvillard/infer,facebook/infer,jvillard/infer,facebook/infer,facebook/infer,jvillard/infer,jvillard/infer,facebook/infer,facebook/infer,facebook/infer,facebook/infer,jvillard/infer