[devel] Added copyright statement to pngdebug.h

and removed a redundant line from the copyright info in pngconf.h
diff --git a/pngconf.h b/pngconf.h
index 0fbc8d8..986a27d 100644
--- a/pngconf.h
+++ b/pngconf.h
@@ -2,7 +2,7 @@
 /* pngconf.h - machine configurable file for libpng
  *
  * libpng version 1.5.0beta12 - March 8, 2010
- * For conditions of distribution and use, see copyright notice in png.h
+ *
  * Copyright (c) 1998-2010 Glenn Randers-Pehrson
  * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
  * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
diff --git a/pngdebug.h b/pngdebug.h
index cdd5d29..8d696d7 100644
--- a/pngdebug.h
+++ b/pngdebug.h
@@ -1,6 +1,15 @@
-/* pngdebug.h
+
+/* pngdebug.h - Debugging macros for libpng, also used in pngtest.c
  *
- * Debugging macros, also used in pngtest.c
+ * Copyright (c) 1998-2010 Glenn Randers-Pehrson
+ * (Version 0.96 Copyright (c) 1996, 1997 Andreas Dilger)
+ * (Version 0.88 Copyright (c) 1995, 1996 Guy Eric Schalnat, Group 42, Inc.)
+ *
+ * Last changed in libpng version 1.5.0 - March 8, 2010
+ *
+ * This code is released under the libpng license.
+ * For conditions of distribution and use, see the disclaimer
+ * and license in png.h
  */
 
 /* Define PNG_DEBUG at compile time for debugging information.  Higher