Remove button needs true page/post id

This is for the remove button in the cart. It is getting the wrong query arg for the post id in a situation where you are running a loop on a page and have the cart loading inside that loop somewhere. The global $post var is actually not the true post object for the page or post we are on.

If we use $wp_query instead, we will get the id of the parent page no matter what loops might be running on the page.