Remove redundant check for PTRACE_LISTEN availability
Remove redundant check for PTRACE_LISTEN availability

As ptrace.h already ensures that PTRACE_LISTEN is defined,
there is no need to check this fact in other places.

* strace.c (ptrace_restart): Do not check that PTRACE_LISTEN is defined.

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