DuplicatingThread: Release tracks in threadLoop

Test: Instrumented test with mutex tracking
Bug: 315402182
Change-Id: I5b3fd4400f3d39a8258c5cd2ebb6e64cd8acdc1f
diff --git a/services/audioflinger/Threads.h b/services/audioflinger/Threads.h
index 9477795..ea994a5 100644
--- a/services/audioflinger/Threads.h
+++ b/services/audioflinger/Threads.h
@@ -1849,6 +1849,7 @@
     void threadLoop_sleepTime() final REQUIRES(ThreadBase_ThreadLoop);
     ssize_t threadLoop_write() final REQUIRES(ThreadBase_ThreadLoop);
     void threadLoop_standby() final REQUIRES(ThreadBase_ThreadLoop);
+    void threadLoop_exit() final REQUIRES(ThreadBase_ThreadLoop);
     void cacheParameters_l() final REQUIRES(mutex(), ThreadBase_ThreadLoop);
 
 private: