logcat: -f run in background

(cherry pick from commit 3ef730c57f88ac24b0d6b021e43fc344d602fe36)

- if saving to file, set SP_BACKGROUND policy
- if saving to file, set BATCH priority
- sort include files

Bug: 19608716
Change-Id: I00acb8b8db0d2ff9ff36c97f9e74604d31938376
2 files changed