Camera: derive post RAW sensitivity keys for BC

Derive post RAW sensitivity keys for devices
earlier than HAL3.4.

Bug: 27950762
Change-Id: Icc2232cb722c61a5878a81706885303b15ddee3e
diff --git a/services/camera/libcameraservice/common/CameraModule.h b/services/camera/libcameraservice/common/CameraModule.h
index 36822c7..1a1c274 100644
--- a/services/camera/libcameraservice/common/CameraModule.h
+++ b/services/camera/libcameraservice/common/CameraModule.h
@@ -57,8 +57,10 @@
 private:
     // Derive camera characteristics keys defined after HAL device version
     static void deriveCameraCharacteristicsKeys(uint32_t deviceVersion, CameraMetadata &chars);
+    // Helper function to append available[request|result|chars]Keys
+    static void appendAvailableKeys(CameraMetadata &chars,
+            int32_t keyTag, const Vector<int32_t>& appendKeys);
     status_t filterOpenErrorCode(status_t err);
-
     camera_module_t *mModule;
     KeyedVector<int, camera_info> mCameraInfoMap;
     Mutex mCameraInfoLock;