adb: detect some spin loops and abort.

Track pending fdevents, and abort if we see an fdevent ready for
read/write for 5 minutes continuously.

Also, add a service that intentionally starts spinning, to test this.

Test: manually changed timeout to a minute, `adb raw spin`
Change-Id: Ibfa5e7e654996587f745887cb04987b982d79bed
2 files changed