Pull upstream v0_42

That is, merge commit '3b2c2d61c05534981b07590500a8530634811578' of the
sso://android.git.corp.google.com/platform/external/kythe, resolve conflict in
kythe/java/com/google/devtools/kythe/extractors/java/JavaCompilationUnitExtractor.java
and update METADATA

Test: build clang-tools and build-tools with it, verify kzip files
Change-Id: I5b41bf90fed5a7db811c1a90f0e3f77795c1da1f