Baseline: f7829f85

Cherry picks:

   + eee0d9df:
     Add an option retention option to proto_library.

Incompatible changes:

  - `--experimental_execution_graph_log` no longer exists. Current
    users that want local logs need to pass
    `--experimental_enable_execution_graph_log
    --experimental_execution_graph_log_path=/some/local/path`.
    Current users that want logs uploaded to BEP need to pass
    `--experimental_enable_execution_graph_log
    --experimental_stream_log_file_uploads`.
  - Remove 'darwin' as a CPU value, use 'darwin_x86_64' instead

Important changes:

  - Added `native.module_name()` and `native.module_version()` to
    allow BUILD macro authors to acquire information about which
    Bazel module the current repo is associated with.
  - Add `--skip_incompatible_explicit_targets` option
  - Remove 'darwin' as a CPU value, use 'darwin_x86_64' instead

This release contains contributions from many people at Google, as well as Benjamin Peterson, Benjamin Sigonneau, Ed Schouten, Fabian Meumertzheim, hvd, Keith Smiley, Malte Poll, Marc Zych.