build fix: missing #include <ndgrf.hxx>

Change-Id: I72caa16d3c5b5698226cc7d3f07d3d32820032d8
diff --git a/sw/source/filter/html/wrthtml.cxx b/sw/source/filter/html/wrthtml.cxx
index bba1108..54afa80 100644
--- a/sw/source/filter/html/wrthtml.cxx
+++ b/sw/source/filter/html/wrthtml.cxx
@@ -55,6 +55,7 @@
 #include <docary.hxx>
 #include <pam.hxx>
 #include <doc.hxx>
+#include <ndgrf.hxx>
 #include <ndtxt.hxx>
 #include <mdiexp.hxx>
 #include <fltini.hxx>