examples/ip_pipeline: fix build in old environments
examples/ip_pipeline: fix build in old environments

This patch fixes build errors on linux kernels such as
SuSE 11-SP2/3(64 bits), etc.

Error Log:
	error: implicit declaration of function 'WIFEXITED'
	error: implicit declaration of function 'WEXITSTATUS'

Fixes: ed0b2d020159 ("examples/ip_pipeline: add more ports")

Signed-off-by: Jasvinder Singh <97b766ecf460b59e2781d4fc0469065206870f5c@intel.com>
Acked-by: Cristian Dumitrescu <25468b8a3698eeb3c368247f8635924bb4a1ce2c@intel.com>

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