add selinux/smack cfg alias

[xtqqczze]

Fixes pre-commit hook failures on non-Linux platforms by adding proper #[cfg(target_os = "linux")] guards to selinux/smack feature gates.

Contributes to #11019

Closes #10995

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/date/resolution. tests/date/resolution is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/rm/isatty. tests/rm/isatty is passing on 'main'. Maybe you have to rebase?
GNU test failed: tests/tail/retry. tests/tail/retry is passing on 'main'. Maybe you have to rebase?
Skip an intermittent issue tests/pr/bounded-memory (fails in this run but passes in the 'main' branch)
Note: The gnu test tests/cp/link-heap is now being skipped but was previously passing.
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.

[github-actions]

GNU testsuite comparison:

Congrats! The gnu test tests/date/date-locale-hour is no longer failing!
Note: The gnu test tests/cp/link-heap is now being skipped but was previously passing.
Note: The gnu test tests/dd/no-allocate is now being skipped but was previously passing.
Note: The gnu test tests/seq/seq-epipe is now being skipped but was previously passing.
Note: The gnu test tests/tail/pipe-f is now being skipped but was previously passing.

[github-actions]

GNU testsuite comparison:

Note: The gnu test tests/cut/cut-huge-range is now being skipped but was previously passing.