Add reference to indexer Pid to task status

When we run re-compaction stage we start second index updater from
view compactor. In this case couch_task_status:all would return two
identical entries for the same `design_document` and `shard`. Which is
very confusing. Add reference to indexer Pid to disambiguate them.
For the recompaction case the indexer_pid will be pointing to compaction task.
1 file changed
tree: fe75d4a925d9cb285a3c383eb8e999c60f94c646
  1. .travis.yml
  3. include/
  4. priv/
  5. src/
  6. test/