lorder: Undeprecate.

While lorder is not required by our current toolchain (or any toolchain
we've used in the past decade or two), it still occasionally shows up
in build systems of third party software, including The Open Group's
UNIX conformance test suite, and the maintenance cost is negligible.

MFC after: 1 week
Sponsored by: Klara, Inc.
Reviewed by: imp, allanjude, emaste
Differential Revision: https://reviews.freebsd.org/D44135