basic + fundamental: Clean up includes

Split out of #37344.

src/basic/escape.c

@@ -1,13 +1,12 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 
-#include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "alloc-util.h"
 #include "escape.h"
 #include "hexdecoct.h"
-#include "macro.h"
+#include "string-util.h"
 #include "strv.h"
 #include "utf8.h"
 
@@ -300,6 +299,9 @@ ssize_t cunescape_length_with_prefix(const char *s, size_t length, const char *p
 
         /* Undoes C style string escaping, and optionally prefixes it. */
 
+        if (length == SIZE_MAX)
+                length = strlen(s);
+
         pl = strlen_ptr(prefix);
 
         ans = new(char, pl+length+1);