OpenGL2: Don't bind null framebuffers when not using framebuffers.

code/renderergl2/tr_fbo.c

@@ -230,6 +230,12 @@ FBO_Bind
 */
 void FBO_Bind(FBO_t * fbo)
 {
+	if (!glRefConfig.framebufferObject)
+	{
+		ri.Printf(PRINT_WARNING, "FBO_Bind() called without framebuffers enabled!\n");
+		return;
+	}
+
 	if (glState.currentFBO == fbo)
 		return;
 		

code/renderergl2/tr_init.c

@@ -951,7 +951,9 @@ void GL_SetDefaultState( void )
 	qglColor4f (1,1,1,1);
 
 	GL_BindNullTextures();
-	GL_BindNullFramebuffers();
+
+	if (glRefConfig.framebufferObject)
+		GL_BindNullFramebuffers();
 
 	qglEnable(GL_TEXTURE_2D);
 	GL_TextureMode( r_textureMode->string );