s3: torture: Fix return values

s3: torture: Fix return values

Torture tests should return true on success and false on failure.
Returning -1 is the same as returning true and returning 0 is the same
as returning false. Change the return values to true and false to fix
the return values.

Detected by the help of cppcheck.

Signed-off-by: Rikard Falkeborn <rikard.falkeborn@gmail.com>
Reviewed-by: Ralph Böhme <slow@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>
Autobuild-User(master): Jeremy Allison <jra@samba.org>
Autobuild-Date(master): Sun May 19 18:48:01 UTC 2019 on sn-devel-184