unexpected behavior of tempfile.TemporaryFile() for O_TMPFILE

Bug report

When O_TMPFILE is available:

1. tempfile.TemporaryFile(mode='wb') opens with O_RDWR instead of O_WRONLY, the opener callback ignores mode argument and always use _bin_openflags
2. _bin_openflags has both O_CREAT and O_EXCL set, the opener callback removes O_CREAT from flags but leave O_EXCL, this is an undefined behavior according to Linux open(2) manpage

Your environment

• CPython versions tested on: 3.10
• Operating system and architecture: Linux x86_64

Linked PRs

• gh-133235

先閱讀 tempfile.TemporaryFile 及其 opener 回呼，重點關注 O_TMPFILE 可用時如何使用 mode 引數和 _bin_openflags。檢查 Linux open(2) 對 O_CREAT 和 O_EXCL 的行為，然後驗證二進位寫入模式使用了預期的存取旗標，而不存在未定義的旗標組合。