filesystems/httpdirfs: fix build on 32-bits

../src/link.c:998:55: error: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Werror,-Wformat]
  998 |     snprintf(range_str, sizeof(range_str), "%lu-%lu", start, end);
      |                                             ~~~       ^~~~~
      |                                             %zu
../src/link.c:998:62: error: format specifies type 'unsigned long' but the argument has type 'size_t' (aka 'unsigned int') [-Werror,-Wformat]
  998 |     snprintf(range_str, sizeof(range_str), "%lu-%lu", start, end);
      |                                                 ~~~          ^~~
      |                                                 %zu
2 errors generated.

filesystems/httpdirfs/files/patch-src_link.c

@@ -0,0 +1,11 @@
+--- src/link.c.orig	2025-01-12 11:28:19 UTC
++++ src/link.c
+@@ -995,7 +995,7 @@ static CURL *Link_download_curl_setup(Link *link, size
+     size_t end = start + req_size - 1;
+
+     char range_str[64];
+-    snprintf(range_str, sizeof(range_str), "%lu-%lu", start, end);
++    snprintf(range_str, sizeof(range_str), "%zu-%zu", start, end);
+     lprintf(debug, "%s: %s\n", link->linkname, range_str);
+
+     CURL *curl = Link_to_curl(link);