Flag --incompatible_no_implicit_file_export will break Flogger in a future Bazel release

Incompatible flag --incompatible_no_implicit_file_export will be enabled by default in a future Bazel release [1], thus breaking Flogger.

The flag is documented here: https://github.com/bazelbuild/bazel/issues/10225

Please check the following CI builds for build and test results:

* Ubuntu 16.04, OpenJDK 8

Never heard of incompatible flags before? We have [documentation](https://docs.bazel.build/versions/master/backward-compatibility.html) that explains everything.

If you don't want to receive any future issues for Flogger or if you have any questions,
please file an issue in https://github.com/bazelbuild/continuous-integration

**Important**: Please do NOT modify the issue title since that might break our tools.

[1] The target release hasn't been determined yet. Our tool will update the issue title once the flag flip has been scheduled.