[metacity] window-props: fix build warnings

[Alberts Muktupāvels <muktupavels src gnome org>]

commit a6bb1e4b4e1ceae76405056025e7990676559689
Author: Alberts Muktupāvels <alberts muktupavels gmail com>
Date:   Sun Sep 20 18:32:06 2015 +0300

    window-props: fix build warnings

 src/core/window-props.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/core/window-props.c b/src/core/window-props.c
index f1e1be0..54d3ed2 100644
--- a/src/core/window-props.c
+++ b/src/core/window-props.c
@@ -50,6 +50,7 @@
 #include <pwd.h>
 
 #ifdef HAVE_GTOP
+#define TIME_WITH_SYS_TIME 1
 #include <glibtop/procuid.h>
 #include <errno.h>
 #include <pwd.h>