abbrev_sha1_in_line: don't leak memory

`split` is of type `struct strbuf **`, and currently we are leaking split
itself as well as each element in split[i]. We have a dedicated free
function for `struct strbuf **`, which takes care of freeing all
related memory.

Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

wt-status.c

@@ -1063,9 +1063,7 @@ static void abbrev_sha1_in_line(struct strbuf *line)
 				strbuf_addf(line, "%s", split[i]->buf);
 		}
 	}
-	for (i = 0; split[i]; i++)
-		strbuf_release(split[i]);
-
+	strbuf_list_free(split);
 }
 
 static void read_rebase_todolist(const char *fname, struct string_list *lines)