Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Rename usr.bin/elfcopy to usr.bin/objcopy

We always install ELF Tool Chain's elfcopy as objcopy, so to avoid
confusion rename the src directory containing our reach-over Makefile
to match.

Requested by: jhb
Sponsored by: The FreeBSD Foundation