fix shared memory leak

Hi corosync master,
Recently, i find two problems of corosync:
1. shared memory leak:
if we run 'corosync -v' or 'corosync --help' or 'corosync -invalidparameters', after corosync exits, it will leave one qb-corosync-xxx-blackbox files under '/dev/shm', which will introduce memory leak.
2. corosync doesn't execute signal handlers when it receives SIGSEGV or SIGABRT signal.

Please help to check below patch for these two problems. thanks a lot.