Make log creation via statsd asynchronous.

This CL creates a new instance of async_task just to handle log
creation asynchronously due to two reasons:
1. Keystore2 starts much earlier than statsd and waits for it.
2. We want to take calling statsd API out of the critical path.

Bug: 185831595
Test: statsd_testdrive script
Change-Id: I79494edda1b195b0120e26d38ccc3e120977166b
1 file changed