sh: increase likelihood of failure on syntax error.
sh: increase likelihood of failure on syntax error.

_wvcheck would accidentally assume success if [] had a syntax error parsing
its input.  Now we invert the check for -eq 0 instead of directly using the
output of -ne 0.

This had covered up a problem on MacOS where /bin/sh doesn't understand
"echo -n".  (It actually prints "-n")  To avoid the problem, switch to using
printf, which is more POSIXy.

apenwarr/wvtest,apenwarr/wvtest,apenwarr/wvtest,apenwarr/wvtest,apenwarr/wvtest,apenwarr/wvtest,apenwarr/wvtest