uniq: Fix flaky test gnu_tests

[BenWiederhake]

The testcase tries to write to the stdin pipe while the process under test is simultaneously exiting with an error code. Naturally, this is a race, and we should ignore any stdin write errors. However, adding this feature to the list makes it even more unreadable, and adds no real value, so let's skip the input data entirely.

This flake causes real problems.

[BenWiederhake]

Changes since last push: Changed "F" to "f" in commit subject. (That seems to be the style of this project.)

[github-actions]

GNU testsuite comparison:

Skipping an intermittent issue tests/tail/inotify-dir-recreate (passes in this run but fails in the 'main' branch)

[BenWiederhake]

These CI flakes are maddening.

--- TRY 3 STDERR:        coreutils::tests common::util::tests::test_uchild_when_run_no_wait_with_a_non_blocking_util ---
thread 'main' panicked at tests/common/util.rs:3117:13:
Assertion failed: child process is still alive.

Looks like Android CI just seriously took over 5 seconds to execute echo "hello world", three times in a row.

There's not much I can do, and more importantly: That doesn't mean there's anything wrong with this PR. I'll just ignore it.

[cakebaker]

Thanks :)