tests/caps.c: use libtests
tests/caps.c: use libtests

* tests/caps.c (main): Use perror_msg_and_skip.

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