K 10
svn:author
V 6
kevans
K 8
svn:date
V 27
2019-12-12T01:33:45.448631Z
K 7
svn:log
V 461
usr.sbin/ntp: don't emit versions w/ make -s

<sys.mk> defines ECHO=echo when not using make -s, and ECHO=true when using
make -s.

export ECHO for ntp products and use it in the mkver script to echo the
version. This suppresses the output as appropriate. ECHO is given a default
value to make sure things still work as expected for anyone that isn't
redefining ECHO.

Reviewed by:	cy
MFC after:	1 week
Differential Revision:	https://reviews.freebsd.org/D22101

END