Added use_adpf_cpu_hint method to flagmanager

Bug: 195990840
Test: make;

Check output of:
adb shell dumpsys SurfaceFlinger | grep -A 10 "FlagManager"

Change-Id: I7d81808a33abc87eeb32a2b90d8ada6cd458f8e7
diff --git a/services/surfaceflinger/FlagManager.h b/services/surfaceflinger/FlagManager.h
index 65e30a4..24d83a2 100644
--- a/services/surfaceflinger/FlagManager.h
+++ b/services/surfaceflinger/FlagManager.h
@@ -31,6 +31,8 @@
 
     int64_t demo_flag() const;
 
+    bool use_adpf_cpu_hint() const;
+
 private:
     friend class FlagManagerTest;