ssh/terminal: fix line endings handling in ReadPassword

Fixes golang/go#16552

Change-Id: I18a9c9b42fe042c4871b3efb3f51bef7cca335d0
Reviewed-on: https://go-review.googlesource.com/25355
Reviewed-by: Adam Langley <alangley@gmail.com>
Reviewed-by: Adam Langley <agl@golang.org>
4 files changed