Fix `compactify` scripted test failure.

Travis CI stopped allowing long file names on its file system. We need
to explicitly set lower limit on file name length using
`-Xmax-classfile-name` Scala compiler option. We set the limit to 240
characters.

Fixes #1553

sbt/src/sbt-test/source-dependencies/compactify/build.sbt

@@ -2,3 +2,8 @@ TaskKey[Unit]("output-empty") <<= classDirectory in Configurations.Compile map {
 	def classes = (outputDirectory ** "*.class").get
 	if(!classes.isEmpty) error("Classes existed:\n\t" + classes.mkString("\n\t")) else ()
 }
+
+// apparently Travis CI stopped allowing long file names
+// it fails with the default setting of 255 characters so
+// we have to set lower limit ourselves
+scalacOptions ++= Seq("-Xmax-classfile-name", "240")