This commit fixes the case where the string buffer may not have
a null terminator if the source string's length is equal to the
buffer size.
Coverity issue: 141069
Fixes: f8be1786b1b8 ("app/crypto-perf: introduce performance test application")
Signed-off-by: Aleksander Gajewski <aleksanderx.gajewski@intel.com>
Acked-by: Pablo de Lara <pablo.de.lara.guarch@intel.com>