For prepare.services, avoid empty classpath entries by only selecting jvm targets that have services defined
Review Request #3058 - Created Oct. 30, 2015 and submitted
|gmalmquist, jsirois, zundel|
PrepareServices should only select targets which actually have services. I don't actually know why the previous logic (to select all JvmTargets) existed though, so hoping reviewers have insight there.
This prevents creating empty classpath entries for all JvmTargets (which significantly slows down classloading time).