Fix fcntl(F_DUPFD) to make it comply with min_fd

[sangho2]

This PR fixes a bug of the current fcntl(F_DUPFD) implementation. fcntl(F_DUPFD) should return an fd greater than or equal to the arg (min_fd) but it doesn't.

[CvvT]

Weidong has a similar fix but do not require adding a new interface to the LiteBox:

litebox/litebox_shim_linux/src/syscalls/file.rs

Lines 4362 to 4369 in b0bca9f

	} else if let Some(min_fd) = min_fd {
	#[allow(clippy::maybe_infinite_iter)]
	let raw_fd = (min_fd..)
	.find(|&raw_fd| !rds.is_alive(raw_fd))
	.expect("raw fd search should always find a slot");
	let success = rds.fd_into_specific_raw_integer(fd, raw_fd);
	assert!(success);
	Ok(raw_fd)

[sangho2]

I did have a similar fix but there is a potential TOCTOU race.

[CvvT]

why is that? rds is locked at the top.

[sangho2]

Found that my old one and Weidong's one are similar but different. Revised this PR.
Draft for now because this PR is not urgent.

[github-actions]

🤖 SemverChecks 🤖 No breaking API changes detected

Note: this does not mean API is unchanged, or even that there are no breaking changes; simply, none of the detections triggered.