Fix inconsistent #include style

Signed-off-by: Pekka Paalanen <ppaalanen@gmail.com>
diff --git a/clients/flower.c b/clients/flower.c
index 5ad58f1..7743b44 100644
--- a/clients/flower.c
+++ b/clients/flower.c
@@ -33,7 +33,7 @@
 #include <sys/time.h>
 #include <glib.h>
 
-#include "wayland-client.h"
+#include <wayland-client.h>
 #include "window.h"
 
 static void