timerfd, timerfd_create: mark return code with RVAL_FD flag

* time.c (sys_timerfd, sys_timerfd_create): Set RVAL_FD flag
in the return code.
diff --git a/time.c b/time.c
index aa065f2..dfddc45 100644
--- a/time.c
+++ b/time.c
@@ -636,7 +636,7 @@
 	tprints(", ");
 	printitv(tcp, tcp->u_arg[3]);
 
-	return RVAL_DECODED;
+	return RVAL_DECODED | RVAL_FD;
 }
 
 SYS_FUNC(timerfd_create)
@@ -645,7 +645,7 @@
 	tprints(", ");
 	printflags(timerfdflags, tcp->u_arg[1], "TFD_???");
 
-	return RVAL_DECODED;
+	return RVAL_DECODED | RVAL_FD;
 }
 
 SYS_FUNC(timerfd_settime)