Pass filename mappings to C++ and Java extractors.

Android builds by default put artifacts into out/ subdirectory of
the source tree, causing the extractor to record their names as
relative. The indexer considers such files as sources, which is wrong.
Fortunately, the extractor can be fed a set of filename rewriting
rules (see build/tools/vnames.json).
Also, undo previous unsuccessful attempt use to absolute path for the
output directory to distinguish between source code and artifacts.

Bug: 141385476
Test: run the build, inspect compilation units of the kzip file
Change-Id: I89ec3aed8fd14f43ea6e0b226d54f643346f6125