examples/performance-thread: check thread creation
examples/performance-thread: check thread creation

There was a call for thread create function without result check.
Added result check and message printout after failure.

Coverity issue: 143441
Fixes: 433ba6228f9a ("examples/performance-thread: add pthread_shim app")

Signed-off-by: Jacek Piasecki <5e1ddc2c85b7acbcba75e0e83b3bb6ce7fe01339@intel.com>
Acked-by: Michal Jastrzebski <99bb29f284bc46c0a62a09be83edd00b1cccc1e5@intel.com>

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