tr(1): Capsicumify

[cem]

Summary

This is a straightforward single input, single output program for
capsicum.

Test Plan

• tr abc ddd (tty input)
• echo abcdef | tr abc ddd
• echo abcdef | LANG=ko_KR.UTF-8 tr "[:lower:]" "[:upper:]"

[bapt]

What about stderr?
for stdin you probably want to check EBADF because STDIN can be closed

[cem]

In D7928#164224, @bapt wrote:

What about stderr?

Sure.

for stdin you probably want to check EBADF because STDIN can be closed

I guess it *can* be closed. But that's kind of a silly thing for someone to do before executing tr. Do we care?

[cem]

Restrict stderr too.