Invert final blit in the OpenGL bindings

We want all of NXT to have the origin in the top left. OpenGL's origin
is the bottom left instead. We are doing a blit already to decouple
the NXT render targets from the OpenGL default framebuffer. Take
advantage of this and invert the blit to make the OpenGL's backend
origin be top left.

src/utils/OpenGLBinding.cpp

@@ -81,7 +81,7 @@ namespace utils {
         nxtSwapChainError Present() {
             glBindFramebuffer(GL_READ_FRAMEBUFFER, mBackFBO);
             glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
-            glBlitFramebuffer(0, 0, mWidth, mHeight, 0, 0, mWidth, mHeight, GL_COLOR_BUFFER_BIT,
+            glBlitFramebuffer(0, 0, mWidth, mHeight, 0, mHeight, mWidth, 0, GL_COLOR_BUFFER_BIT,
                               GL_NEAREST);
             glfwSwapBuffers(mWindow);