gcompat: gtk_widget_set_can_focus() for below 2.18

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/gcompat.c b/gcompat.c
index 7b0810b..5944df0 100644
--- a/gcompat.c
+++ b/gcompat.c
@@ -47,3 +47,13 @@
 }
 
 #endif
+
+#if GTK_MAJOR_VERSION <= 2 && GTK_MINOR_VERSION < 18
+void gtk_widget_set_can_focus(GtkWidget *widget, gboolean can_focus)
+{
+	if (can_focus)
+		GTK_WIDGET_SET_FLAGS(widget, GTK_CAN_FOCUS);
+	else
+		GTK_WIDGET_UNSET_FLAGS(widget, GTK_CAN_FOCUS);
+}
+#endif