update thirdparty, add build script

thirdparty/libpng/scripts/vers.c

@@ -0,0 +1,19 @@
+
+/* vers.c - define format of libpng.vers
+ *
+ * Last changed in libpng version 1.6.16 [December 22, 2014]
+ * Copyright (c) 2011-2014 Glenn Randers-Pehrson
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
+ */
+
+#define PNG_EXPORTA(ordinal, type, name, args, attributes)\
+        PNG_DFN " @" SYMBOL_PREFIX "@@" name "@;"
+
+PNG_DFN "@" PNGLIB_LIBNAME "@ {global:"
+
+#include "../png.h"
+
+PNG_DFN "local: *; };"