test/stack: check stack performance

test/stack: check stack performance

stack_perf_autotest tests the following with one lcore:
- Cycles to attempt to pop an empty stack
- Cycles to push then pop a single object
- Cycles to push then pop a burst of 32 objects

It also tests the cycles to push then pop a burst of 8 and 32 objects with
the following lcore combinations (if possible):
- Two hyperthreads
- Two physical cores
- Two physical cores on separate NUMA nodes
- All available lcores

Signed-off-by: Gage Eads <gage.eads@intel.com>
Reviewed-by: Olivier Matz <olivier.matz@6wind.com>