linux(4): Implement poll system call via linux_common_ppol()

for the sake of converting events to/from native.

MFC after:	2 weeks

sys/amd64/linux/syscalls.master

@@ -82,8 +82,8 @@
 		    struct l_newstat *buf
 		);
 	}
-7	AUE_POLL	NOPROTO {
-		int poll(
+7	AUE_POLL	STD {
+		int linux_poll(
 		    struct pollfd *fds,
 		    u_int nfds,
 		    int timeout

sys/amd64/linux32/syscalls.master

@@ -887,8 +887,8 @@
 	}
 166	AUE_NULL	UNIMPL	vm86
 167	AUE_NULL	UNIMPL	query_module
-168	AUE_POLL	NOPROTO {
-		int poll(
+168	AUE_POLL	STD {
+		int linux_poll(
 		    struct pollfd *fds,
 		    unsigned int nfds,
 		    int timeout

sys/arm/linux/syscalls.master

@@ -744,8 +744,8 @@
 	}
 166	AUE_NULL	UNIMPL  ; was linux_vm86
 167	AUE_NULL	UNIMPL  ; was linux_query_module
-168	AUE_POLL	NOPROTO	{
-		int poll(
+168	AUE_POLL	STD	{
+		int linux_poll(
 		    struct pollfd* fds,
 		    unsigned int nfds,
 		    long timeout

sys/compat/linux/linux_misc.c

@@ -2858,3 +2858,23 @@ linux_getcpu(struct thread *td, struct linux_getcpu_args *args)
 		error = copyout(&node, args->node, sizeof(l_int));
 	return (error);
 }
+
+#if defined(__i386__) || defined(__amd64__)
+int
+linux_poll(struct thread *td, struct linux_poll_args *args)
+{
+	struct timespec ts, *tsp;
+
+	if (args->timeout != INFTIM) {
+		if (args->timeout < 0)
+			return (EINVAL);
+		ts.tv_sec = args->timeout / 1000;
+		ts.tv_nsec = (args->timeout % 1000) * 1000000;
+		tsp = &ts;
+	} else
+		tsp = NULL;
+
+	return (linux_common_ppoll(td, args->fds, args->nfds,
+	    tsp, NULL, 0));
+}
+#endif /* __i386__ || __amd64__ */

sys/i386/linux/syscalls.master

@@ -912,8 +912,8 @@
 		int linux_vm86(void);
 	}
 167	AUE_NULL	UNIMPL	query_module
-168	AUE_POLL	NOPROTO {
-		int poll(
+168	AUE_POLL	STD {
+		int linux_poll(
 		    struct pollfd *fds,
 		    unsigned int nfds,
 		    long timeout