sed: add -z.

Used to construct SELinux policies in the AOSP build.

I left loopfiles_lines with its hard-coded '\n' because although cut(1)
also has a -z option, I can't find any case where it's used in any of
the codebases searchable by me. (And fmt(1), the other user, doesn't
even have the option.) YAGNI.

Bug: http://b/122744241
4 files changed