Align up java-lib-files and java-lib-deps.

- For host Java libraries, java-lib-files should return javalib.jar.
- Host dalvik Java libraries are special: factor out
  host-dex-java-lib-files.
- Be explict that jack-lib-deps equals jack-lib-files.

Bug: 27451686
Change-Id: I9235384354e119ef7ebbf29b7e525d1ceea242e0