BUG/MEDIUM: list: correct fix for LIST_POP_LOCKED's removal of last element

As seen with Olivier, in the end the fix in commit 285192564 ("BUG/MEDIUM:
list: fix LIST_POP_LOCKED's removal of the last pointer") is wrong,
the code there was right but the bug was triggered by another bug in
LIST_ADDQ_LOCKED() which doesn't properly update the list's head by
inserting in the wrong order.

This will have to be backported if the commit above is backported.
1 file changed