Make the build aware of Scala 2.11 modularization
Avoid inferring by-name type argument to function1Covariant

This is (in general) unsound as shown in SI-7899 and no longer
supported in Scala 2.11.

See https://issues.scala-lang.org/browse/SI-7899

This change should be binary compatible as it just introduces a new
method, so we could/should backport to 7.0.x.