successful pigz check returns non-zero exit code

[gitmstoute]

updating so it will work with process_runner and return an exit code of 0.

"pigz -q" is used for the check in 1.5.4.

mstoute@mstoute:~$ pigz -q  
mstoute@mstoute:~$ echo $?  
22  
mstoute@mstoute:~$ pigz --version  
pigz 2.3.4  
mstoute@mstoute:~$ echo $?  
0