Only write Class-Path to our .jar when there's an actual classpath!
Only write Class-Path to our .jar when there's an actual classpath!

This fixes running Scala for me, but it's probably not enough for a proper
solution. Still, JVM support is mostly a proof-of-concept at this point, so I
don't care too much...

jimporter/bfg9000,jimporter/bfg9000,jimporter/bfg9000,jimporter/bfg9000