Use async logging while streaming only

The benefits of reliable output outweigh performance concerns during non-streaming activities.

app/streaming/streamutils.h

@@ -31,4 +31,10 @@ public:
 
     static
     int getDrmFd(bool preferRenderNode);
+
+    static
+    void enterAsyncLoggingMode();
+
+    static
+    void exitAsyncLoggingMode();
 };