opengles emulator: added FPS statistics printout

Make the renderer print FPS statistics every 1 second.
Need to set SHOW_FPS_STATS=1

Change-Id: I69e8c43a779e685ae0b34974d1ef33ad75e7a7e4

tools/emulator/opengl/host/libs/libOpenglRender/FrameBuffer.h

@@ -106,5 +106,9 @@ private:
     EGLSurface m_prevDrawSurf;
     EGLNativeWindowType m_subWin;
     EGLNativeDisplayType m_subWinDisplay;
+
+    int m_statsNumFrames;
+    long long m_statsStartTime;
+    bool m_fpsStats;
 };
 #endif