Cleanup of Zygote files

This CL cleans up some warnings in the ZygoteInit.java and
ZygoteServer.java files.  These warnings were mostly about unused
variables, protection class changes, and dead code.  Some changes
to code in Zygote.java and ZygoteConnection.java were needed due to
function signature changes.

Test: Built and booted image
Merged-In: I6ba33cfcb4729a75dbbd4f908f4b46110d3bb991
Change-Id: I6ba33cfcb4729a75dbbd4f908f4b46110d3bb991