opengles emulator: fixed renderer termination flow

Handling clean exit of the renderer when stopOpenGLRenderer
is called. This is done by openning a connection to the renderer
and flag that it should exit. Added 'clientFlags' field which must
be send after every connection is made to the renderer for this purpose.
The server will wait for running rendering threads to exit and then will
close all EGL/GL resources and will exit. The stopOpenGLRenderer will
return only when the renderer has exited.

Change-Id: I8272b8ea59d5fc78453bb7bd2d25908068869fa7

tools/emulator/opengl/host/include/libOpenglRender/IOStream.h

@@ -88,4 +88,13 @@ private:
     size_t m_free;
 };
 
+//
+// When a client opens a connection to the renderer, it should
+// send unsigned int value indicating the "clientFlags".
+// The following are the bitmask of the clientFlags.
+// currently only one bit is used which flags the server
+// it should exit.
+//
+#define IOSTREAM_CLIENT_EXIT_SERVER      1
+
 #endif