improve performance on linux by removing glFinish()

src/framework/graphics/graphics.cpp

@@ -213,6 +213,7 @@ void Graphics::beginRender()
 
 void Graphics::endRender()
 {
+    glFlush();
 }
 
 void Graphics::setViewportSize(const Size& size)

src/framework/platform/x11window.cpp

@@ -802,7 +802,6 @@ void X11Window::swapBuffers()
 #ifdef OPENGL_ES
     eglSwapBuffers(m_eglDisplay, m_eglSurface);
 #else
-    glFinish();
     glXSwapBuffers(m_display, m_window);
 #endif
 }