curlx: add curlx_rename(), fix to support long filenames on Windows

[vszakats]

Move existing Curl_rename() rename() wrapper from lib to
curlx/fopen, and make it a curlx macro/function. To allow using
the local worker function to fixup long filenames on Windows.

Then fix the Windows-specific rename implementation to support long
filenames. This operation may happen when using a cookie jar, HSTS cache
or alt-svc cache, via libcurl or the curl tool.

Before this patch, when passing a long filename to the above options,
a <random>.tmp file was left on the disk without renaming it to the
filename passed to curl. There was also 1 second delay for each
attempted rename operation.

Also:

• checksrc: ban raw rename() and MoveFileEx*() functions.
• Note: Curl_rename() returned 1 on failure before this patch, while
  curlx_rename() returns -1 after, to match POSIX rename().

Refs:
https://learn.microsoft.com/windows/win32/api/winbase/nf-winbase-movefileexa
https://learn.microsoft.com/windows/win32/fileio/maximum-file-path-limitation

Ref: #20040

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• rebase on windows: fix CreateFile() calls to support long filenames #20040.
• add long filename support to curlx_win32_rename().
• possibly address potentially broken build when UNICODE != _UNICODE.
  Though I believe such build makes little practical sense, let alone supporting it.
  setup-win32.h has protection against mixing them, so UNICODE == _UNICODE
  is guaranteed. Nice!

[Copilot]

Pull request overview

This PR refactors the file rename functionality by introducing curlx_rename with long filename support on Windows, replacing the previous Curl_rename() function. The key change is moving the implementation from standalone files to the existing curlx/fopen module and aligning the error return value with POSIX conventions (-1 for failure instead of 1).

• Adds curlx_win32_rename() with Windows long path support using fix_excessive_path()
• Updates three call sites (hsts.c, cookie.c, altsvc.c) to use the new curlx_rename API
• Adds rename and MoveFileEx* functions to the banned functions list to enforce use of the wrapper

Reviewed changes

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
scripts/checksrc.pl	Adds MoveFileEx, MoveFileExA, MoveFileExW, and rename to banned functions list
lib/rename.h	Removes old header file containing Curl_rename declaration
lib/rename.c	Removes old implementation file
lib/hsts.c	Updates call from Curl_rename() to curlx_rename() and removes now-unnecessary include
lib/curlx/fopen.h	Adds curlx_win32_rename declaration and defines curlx_rename macro
lib/curlx/fopen.c	Implements curlx_win32_rename() with long filename support via fix_excessive_path()
lib/cookie.c	Updates call from Curl_rename() to curlx_rename() and removes include
lib/altsvc.c	Updates call from Curl_rename() to curlx_rename() and removes include
lib/Makefile.inc	Removes rename.c and rename.h from build files list
docs/internals/CODE_STYLE.md	Documents rename and MoveFileEx* as banned functions

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[Copilot]

Pull request overview

Copilot reviewed 10 out of 10 changed files in this pull request and generated 1 comment.

---

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[jay]

Yes when UNICODE is defined we expect _UNICODE and vice versa that's why there's a compile-time sanity check in setup-win32