$NetBSD: patch-ab,v 1.2 2010/10/16 15:50:21 wiz Exp $

Fix compilation with png-1.4, already included upstream.

--- src/impex/png.cxx.orig	2008-08-13 13:15:45.000000000 +0000
+++ src/impex/png.cxx
@@ -270,8 +270,8 @@ namespace vigra {
         // expand gray values to at least one byte size
         if ( color_type == PNG_COLOR_TYPE_GRAY && bit_depth < 8 ) {
             if (setjmp(png->jmpbuf))
-                vigra_postcondition( false,png_error_message.insert(0, "error in png_set_gray_1_2_4_to_8(): ").c_str());
-            png_set_gray_1_2_4_to_8(png);
+                vigra_postcondition( false,png_error_message.insert(0, "error in png_set_expand_gray_1_2_4_to_8(): ").c_str());
+            png_set_expand_gray_1_2_4_to_8(png);
             bit_depth = 8;
         }