[libpng16] Update copyright year to 2018 in png.c

png.c

@@ -1,8 +1,8 @@
 
 /* png.c - location for general purpose libpng functions
  *
- * Last changed in libpng 1.6.33 [September 28, 2017]
- * Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson
+ * Last changed in libpng 1.6.35 [(PENDING RELEASE)]
+ * Copyright (c) 1998-2002,2004,2006-2018 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.)
  *
@@ -817,14 +817,14 @@ png_get_copyright(png_const_structrp png_ptr)
 #  ifdef __STDC__
    return PNG_STRING_NEWLINE \
       "libpng version 1.6.35beta01 - January 8, 2018" PNG_STRING_NEWLINE \
-      "Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson" \
+      "Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson" \
       PNG_STRING_NEWLINE \
       "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
       "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
       PNG_STRING_NEWLINE;
 #  else
    return "libpng version 1.6.35beta01 - January 8, 2018\
-      Copyright (c) 1998-2002,2004,2006-2017 Glenn Randers-Pehrson\
+      Copyright (c) 1998-2002,2004,2006-2018 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.";
 #  endif