Handle the removal of embedded libpng from upstream-svn.
Index: navit/configure.in
===================================================================
--- navit.orig/configure.in	2010-01-28 11:24:34.500803653 +0100
+++ navit/configure.in	2010-01-28 11:24:36.890387435 +0100
@@ -883,7 +883,6 @@
 navit/speech/speech_dispatcher/Makefile
 navit/support/Makefile
 navit/support/espeak/Makefile
-navit/support/libpng/Makefile
 navit/vehicle/Makefile
 navit/vehicle/android/Makefile
 navit/vehicle/file/Makefile