Interferes with scalafix

[avdv]

I tried to use clippy together with scalacenter/scalafix in an SBT project.

Somehow it rendered the scalafix tool almost useless, as it did not work anymore. See scalacenter/scalafix#592

The reason seems to be that the warnings are no longer emitted to the semanticdb file which scalafix acts upon. Here's a raw diff of a semanticdb file with clippy enabled and disabled:

-��������         _root_.sbt."��
+��������         _root_.sbt.��Unused import"��