progs/tests: add additional FBO->window test paths (disabled)

Normally use glReadPixels + glDrawPixels.  Add debug/test paths for
glCopyPixels and glBlitFramebuffer.

progs/tests/fbotest2.c

@@ -33,7 +33,8 @@ CheckError(int line)
 static void
 Display( void )
 {
-   GLubyte *buffer = malloc(Width * Height * 4);
+   GLboolean copyPix = GL_FALSE;
+   GLboolean blitPix = GL_FALSE;
    GLenum status;
 
    CheckError(__LINE__);
@@ -63,6 +64,31 @@ Display( void )
    glutSolidTeapot(2.0);
    glPopMatrix();
 
+   if (copyPix) {
+      glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, MyFB);
+      glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
+      glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, 0);
+      glDrawBuffer(GL_BACK);
+
+      glDisable(GL_DEPTH_TEST);  /* in case window has depth buffer */
+
+      glWindowPos2iARB(0, 0);
+      glCopyPixels(0, 0, Width, Height, GL_COLOR);
+   }
+   else if (blitPix) {
+      glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT, MyFB);
+      glReadBuffer(GL_COLOR_ATTACHMENT0_EXT);
+      glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT, 0);
+      glDrawBuffer(GL_BACK);
+
+      glDisable(GL_DEPTH_TEST);  /* in case window has depth buffer */
+
+      glBlitFramebufferEXT(0, 0, Width, Height,
+                           0, 0, Width, Height,
+                           GL_COLOR_BUFFER_BIT, GL_NEAREST);
+   }
+   else {
+      GLubyte *buffer = malloc(Width * Height * 4);
       /* read from user framebuffer */
       glReadPixels(0, 0, Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
 
@@ -73,6 +99,8 @@ Display( void )
       glDrawPixels(Width, Height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
 
       free(buffer);
+   }
+
    glutSwapBuffers();
    CheckError(__LINE__);
 }