Description: Debian is moving to libpng1.6 while upstream code does not yet
 have that enabled.
Bug-Debian: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=820708
Source: https://github.com/castle-engine/castle-engine/commit/3abd42911bd85bf3782d0fac16439d0ab301d11a

Index: cge/src/images/castlepng_dynamic.inc
===================================================================
--- cge.orig/src/images/castlepng_dynamic.inc
+++ cge/src/images/castlepng_dynamic.inc
@@ -966,6 +966,8 @@ begin
     eventually adjust the used libpng using symlink (in case the
     exact libpng12.so.0 doesn't exist). }
   if PngLibrary = nil then
+    PngLibrary := TDynLib.Load('libpng16.so.16', false);
+  if PngLibrary = nil then
     PngLibrary := TDynLib.Load('libpng.so', false);
   if PngLibrary = nil then
     PngLibrary := TDynLib.Load('libpng14.so', false);