app/test: fix sprintf with strlcat
app/test: fix sprintf with strlcat

sprintf function is not secure as it doesn't check the length of string.
More secure function strlcat is used.

Fixes: 727909c592 ("app/test: introduce dynamic commands list")
Cc: stable@dpdk.org

Signed-off-by: Pallantla Poornima <756fdb0861efad85838173e0a29ad4c7efdfe95b@intel.com>
Reviewed-by: Aaron Conole <aa17ba42a0685b214660ffb377dc7569a94d48c9@redhat.com>

john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk,john-mcnamara-intel/dpdk