Update syncio.nim, fixes "open by FileHandle" doesn't work on Windows (#23456)

## Reprodution
if on Windows:
```Nim
when defined(windows):
  var file: File
  let succ = file.open(<aFileHandle>)
``` 
then `succ` will be false.

If tested, it can be found to fail with errno `22` and message: `Invalid
argument`

## Problem
After some investigations and tests,
I found it's due to the `mode` argument for `fdopen`.


Currently `NoInheritFlag`(`'N'` in Windows) is added to `mode` arg
passed to `_fdopen`, but if referring to
[Windows `_fdopen`
doc](https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/fdopen-wfdopen?view=msvc-170),
you'll find there is no `'N'` describled. That's `'N'` is not accepted
by `_fdopen`.

Therefore, the demo above will fail.

## In Addition
To begin with, technologically speaking, when opening with a
`fileHandle`(or called `fd`), there is no concept of fd-inheritable as
`fd` is opened already.

In POSIX, `NoInheritFlag` is defined as `e`.

It's pointed out in [POSIX `open`
man-doc](https://www.man7.org/linux/man-pages/man3/fopen.3.html) that
`e` in mode is ignored for fdopen(),

which means `e` for `fdopen()` is not wanted, just allowed.

Therefore, better to also not pass `e` to `fdopen`

---

In all, that's this PR.

0 files changed, 0 insertions, 0 deletions