hdr	vfork
sys	vfork

tst	run{
	if	test "$_hdr_vfork" = 1
	then	echo "#include <vfork.h>"
	elif	test "$_sys_vfork" = 1
	then	echo "#include <sys/vfork.h>"
	else	echo '#include <unistd.h>' > $tmp.c
		$cc -E $tmp.c | grep vfork
	fi
}end
