GitLab

* Modify the stream-merging code to output to a pipe instead of a
  Python generator, so that the "symbolize" tool can read both app
  and kernel logs.
* Rename "build_manifest.py" to "prepare_package_inputs.py" to better
  capture the broader scope of that script.
* Add ids.txt generation logic to prepare_package_inputs.py.
* Remove dead codepath for disabling symbolization. Symbolization has
  been forced-on by the build scripts with no issues so far, so having
  an opt-out is unnecessary.


Bug: 772252
Change-Id: I4e01d0fc5ce96521efa6d0d394e629cb5c7985ff
Reviewed-on: https://chromium-review.googlesource.com/c/1474032
Commit-Queue: Wez <wez@chromium.org>
Reviewed-by: Wez <wez@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634879}