tests/memfd_create.c: use libtests
tests/memfd_create.c: use libtests

* tests/memfd_create.c: Use SKIP_MAIN_UNDEFINED.

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