app/test: adjust alignment unit for memcpy performance
app/test: adjust alignment unit for memcpy performance

Decide alignment unit for memcpy perf test based on predefined macros.

Signed-off-by: Zhihong Wang <efad9c89b3a8db7900a2572fdee08ebbff3cfc6b@intel.com>

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