Check whether errno can be trieved from processes
Check whether errno can be trieved from processes

errno is extremely valuable for working out why something went wrong,
but it can't be retrieved by gdb unless the binary links pthread, so for
now I skip those processes.

CodethinkLabs/online-atomic-update,CodethinkLabs/live-atomic-update,CodethinkLabs/live-atomic-update,CodethinkLabs/online-atomic-update