tests: fix accept4.test on systems that lack SOCK_CLOEXEC definition
tests: fix accept4.test on systems that lack SOCK_CLOEXEC definition

* tests/accept4.c: Check that O_CLOEXEC is defined.  Use O_CLOEXEC
instead of SOCK_CLOEXEC.

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