tr: implement support for non-UTF-8 input#354

jgarzik merged 3 commits intorustcoreutils:mainrustcoreutils/posixutils-rs:mainfrom

andrewliebenow:tr-mixed-binary-utf-8-processingandrewliebenow/posixutils-rs:tr-mixed-binary-utf-8-processingCopy head branch name to clipboard