Fix inconsistent #include style

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
diff --git a/clients/smoke.c b/clients/smoke.c
index 061bd6d..6ceade0 100644
--- a/clients/smoke.c
+++ b/clients/smoke.c
@@ -32,7 +32,7 @@
 #include <cairo.h>
 #include <glib.h>
 
-#include "wayland-client.h"
+#include <wayland-client.h>
 #include "window.h"
 
 struct smoke {