Baseline: fa48bc66

Important changes:

  - Baseline coverage files are no longer ignored.
  - select() on `cpu`, `host_cpu`, or `crosstool_top now emits a
    "deprecated flag" warning
  - `--max_idle_secs` now takes system sleep time into account when
    deciding when to shutdown the blaze server.
  - Flip --experimental_enable_starlark_set and enable the Starlark
    set data type by default.

This release contains contributions from many people at Google, as well as Alessandro Patti, Boleyn Su, Eric Riff, Fabian Meumertzheim, Keith Smiley, Kiron, Pareesh Madan, Steve Barrau, Torgil Svensson.