head: catch I/O error with -c 1

[oech3]

$ target/debug/head -c 1 /dev/zero >/dev/full
head: error writing 'standard output': No space left on device (os error 28)
Error flushing stdout: No space left on device (os error 28)

also simplify comments

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/pr/bounded-memory (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/misc/write-errors was skipped on 'main' but is now failing.

[cakebaker]

Thanks!