Notify FilterCallbackScheduler to wake up it while stopping.

Bug: 183057734
Test: atest android.media.tv.tuner.cts
Change-Id: I2b9d45fa7df3f2490893cc24d98c0e0baaaf0c2c

tv/tuner/aidl/default/Filter.cpp

@@ -88,7 +88,11 @@ void FilterCallbackScheduler::start() {
 }
 
 void FilterCallbackScheduler::stop() {
-    mIsRunning = false;
+    {
+        std::unique_lock<std::mutex> lock(mLock);
+        mIsRunning = false;
+        mCv.notify_all();
+    }
     if (mCallbackThread.joinable()) {
         mCallbackThread.join();
     }
@@ -113,6 +117,10 @@ void FilterCallbackScheduler::threadLoopOnce() {
         // okay to send data.
         mCv.wait(lock);
     }
+    if (!mIsRunning) {
+        lock.unlock();
+        return;
+    }
 
     // condition_variable wait locks mutex on timeout / notify
     if (!mCallbackBuffer.empty()) {