libtwrpgui: convert gui to use new ziparchive library

Change-Id: Iea94855257c6d02c2f663c25d390cb1cfb91a727
diff --git a/gui/slider.cpp b/gui/slider.cpp
index 3c5f652..a183d28 100755
--- a/gui/slider.cpp
+++ b/gui/slider.cpp
@@ -40,7 +40,7 @@
 extern "C" {
 #include "../twcommon.h"
 }
-#include "../minuitwrp/minui.h"
+#include "minuitwrp/minui.h"
 
 #include "rapidxml.hpp"
 #include "objects.hpp"