[aravis] realtime: add missing include

[Emmanuel Pacaud <emmanuel src gnome org>]

commit 6b937b16ae3bb0529aa0e1368c96380e9a1d94b4
Author: Emmanuel Pacaud <emmanuel gnome org>
Date:   Fri Jan 22 14:30:16 2016 +0100

    realtime: add missing include

 src/arvrealtime.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/src/arvrealtime.c b/src/arvrealtime.c
index 94e24e7..2322489 100644
--- a/src/arvrealtime.c
+++ b/src/arvrealtime.c
@@ -31,6 +31,7 @@
 #include <arvdebug.h>
 #include <memory.h>
 #include <errno.h>
+#include <sched.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/resource.h>