tests/fstatat64.c: use libtests
tests/fstatat64.c: use libtests

* tests/fstatat64.c: Use SKIP_MAIN_UNDEFINED.

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