aaudio: control MMAP mode using system properties

To facilitate testing of MMAP mode.

Bug: 38268547
Test: set properties, see framesPerBurst in write_sine_callback.cpp
Change-Id: I6e15c563215017f6a5020d89ac312ff8331afc4f
Signed-off-by: Phil Burk <philburk@google.com>
diff --git a/services/oboeservice/AAudioServiceEndpoint.h b/services/oboeservice/AAudioServiceEndpoint.h
index a4ceae6..d0c2f53 100644
--- a/services/oboeservice/AAudioServiceEndpoint.h
+++ b/services/oboeservice/AAudioServiceEndpoint.h
@@ -77,6 +77,7 @@
 
     std::atomic<bool>        mCallbackEnabled;
     int32_t                  mReferenceCount = 0;
+    bool                     mLatencyTuningEnabled = false; // TODO implement tuning
 
     std::mutex               mLockStreams;
     std::vector<AAudioServiceStreamShared *> mRegisteredStreams;