suspend: add benchmarks

Add benchmarks for acquireing wake locks and getting wake lock stats.

Results on cuttlefish:
--------------------------------------------------------------
Benchmark                    Time             CPU   Iterations
--------------------------------------------------------------
BM_acquireWakeLock       37586 ns        26681 ns        25497
BM_getWakeLockStats     770001 ns        89569 ns         8756

Bug: 143284916
Test: SystemSuspendBenchmark
Change-Id: Iaf96bff48a76dd448762d4a827160f5b2b4d4820
2 files changed