prio-queue: fix type of insertion_ctr

In 62e745ced2 (prio-queue: use size_t rather than int for size,
2024-12-20), we have converted `struct prio_queue` to use `size_t` to
track the number of entries in the queue as well as the allocated size
of the underlying array. There is one more counter though, namely the
insertion counter, that is still using an `unsigned` instead of a
`size_t`. This is unlikely to ever be a problem, but it makes one wonder
why some indices use `size_t` while others use `unsigned`. Furthermore,
the mentioned commit stated the intent to also adapt these variables,
but seemingly forgot to do so.

Fix the issue by converting those counters to use `size_t`, as well.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

prio-queue.h

@@ -22,13 +22,13 @@
 typedef int (*prio_queue_compare_fn)(const void *one, const void *two, void *cb_data);
 
 struct prio_queue_entry {
-	unsigned ctr;
+	size_t ctr;
 	void *data;
 };
 
 struct prio_queue {
 	prio_queue_compare_fn compare;
-	unsigned insertion_ctr;
+	size_t insertion_ctr;
 	void *cb_data;
 	size_t alloc, nr;
 	struct prio_queue_entry *array;