Build HalProxy unit tests with a test library ScopedWakelock

Unit tests do not currently build because they cannot find the
ScopedWakelock shared object. Make a test library version of
ScopedWakelock for them.

Test: Build and run atest android.hardware.sensors@2.0-halproxy-unit-tests
Change-Id: Ie8d3eb606ccba3825be2c8102b9a7bc6ea033f65
2 files changed