audio_utils: add Histogram

Add Histogram class that counts events.
It also keeps track of the index of the last event in a bin.
Return zero for out of range indices.

Test: Used by AAudio IsochronousClockModel
Test: libaaudio/tests/test_histogram.cpp
Change-Id: Idf8fa9d9f152218c2f9732cd4b021cafb08f3a2f
1 file changed