Miscellaneous fixes for java compiling

Remove java out directory before compiling to avoid incremental compile
issues.  Move the rspfile out of the out directory so it doesn't get
deleted.  cc->javac in the javac rule.  Don't call javac if there
are no source files.

Change-Id: I0bb06c214da54a587bd9e7c9d17caaf0ed1e595e
2 files changed