the ECHO macro is set to "echo" by default, but it is set to "true" if
make(1) is invoked with the -s option while ECHO_CMD is always set to
the echo command.
that was in standard use up to UNIX 6th Edition and was supplied as osh
with UNIX 7th Edition. Its command language is a sparse subset of those
of modern shells and is mostly common to both sh(1) and csh(1).
PR: 23943
Submitted by: George Reid <greid@ukug.uk.freebsd.org>
