display: Add BufferMirrorMode support for External

- In Buffer mirror mode, the output on the external should be rotated
  based on the primary orientation.
- this is used for the side sync feature.
- buffermirrormode has higher precedence over external orientation
- Add binder interface to enable/disable buffermirror mode

Change-Id: Ibea0af9627d69b4d42453adc868b113d82613437
diff --git a/libhwcomposer/hwc_qclient.h b/libhwcomposer/hwc_qclient.h
index 4cbabef..848d8d2 100644
--- a/libhwcomposer/hwc_qclient.h
+++ b/libhwcomposer/hwc_qclient.h
@@ -61,6 +61,7 @@
     void unsecuring(uint32_t startEnd);
     android::status_t screenRefresh();
     void setExtOrientation(uint32_t orientation);
+    void setBufferMirrorMode(uint32_t enable);
 
     hwc_context_t *mHwcContext;
     const android::sp<android::IMediaDeathNotifier> mMPDeathNotifier;