tests/ipc_msgbuf.c: use libtests
tests/ipc_msgbuf.c: use libtests

* tests/ipc_msgbuf.c (cleanup): New function.
(main): Use it and perror_msg_and_skip.

cuviper/strace,cuviper/strace,cuviper/strace,Saruta/strace,Saruta/strace,cuviper/strace,Saruta/strace,Saruta/strace,cuviper/strace,Saruta/strace