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

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 );