hook: move unsorted_string_list_remove() to string-list.[ch]

Move the convenience wrapper from hook to string-list since
it's a more suitable place. Add a doc comment to the header.

Suggested-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

hook.c

@@ -110,14 +110,6 @@ static void list_hooks_add_default(struct repository *r, const char *hookname,
 	string_list_append(hook_list, hook_path)->util = h;
 }
 
-static void unsorted_string_list_remove(struct string_list *list,
-					const char *str)
-{
-	struct string_list_item *item = unsorted_string_list_lookup(list, str);
-	if (item)
-		unsorted_string_list_delete_item(list, item - list->items, 0);
-}
-
 /*
  * Callback struct to collect all hook.* keys in a single config pass.
  * commands: friendly-name to command map.

string-list.c

@@ -281,6 +281,15 @@ void unsorted_string_list_delete_item(struct string_list *list, int i, int free_
 	list->nr--;
 }
 
+void unsorted_string_list_remove(struct string_list *list, const char *str,
+				 int free_util)
+{
+	struct string_list_item *item = unsorted_string_list_lookup(list, str);
+	if (item)
+		unsorted_string_list_delete_item(list, item - list->items,
+						 free_util);
+}
+
 /*
  * append a substring [p..end] to list; return number of things it
  * appended to the list.

string-list.h

@@ -265,6 +265,14 @@ struct string_list_item *unsorted_string_list_lookup(struct string_list *list,
  */
 void unsorted_string_list_delete_item(struct string_list *list, int i, int free_util);
 
+/**
+ * Remove the first item matching `str` from an unsorted string_list.
+ * No-op if `str` is not found. If `free_util` is non-zero, the `util`
+ * pointer of the removed item is freed before deletion.
+ */
+void unsorted_string_list_remove(struct string_list *list, const char *str,
+				 int free_util);
+
 /**
  * Split string into substrings on characters in `delim` and append the
  * substrings to `list`.  The input string is not modified.