cp, tail: unnecessary pipe call

[oech3]

coreutils/src/uucore/src/lib/features/buf_copy/linux.rs

Lines 44 to 47 in 7ea1211

	// todo: bypass broker pipe this if input or output is pipe. We use this mostly for stream.
	if !crate::pipes::splice_unbounded_broker(src, dest)? {
	return Ok(());
	}

> echo 1|strace -c -e pipe,pipe2 cp /dev/stdin /dev/stdout
1
% time     seconds  usecs/call     calls    errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00    0.000007           7         1           pipe