Update libpng 1.6.22beta

Includes SSE filter optimizations that will reduce decode runtime
by about 30% on Intel CPUs.

BUG:27264258
Change-Id: Ia7b9aeaddb43381c71e40607b5ccb40ebd3f5a31
diff --git a/pnginfo.h b/pnginfo.h
index 4bd264b..361ed8b 100644
--- a/pnginfo.h
+++ b/pnginfo.h
@@ -2,7 +2,7 @@
 /* pnginfo.h - header file for PNG reference library
  *
  * Last changed in libpng 1.6.1 [March 28, 2013]
- * Copyright (c) 1998-2013 Glenn Randers-Pehrson
+ * Copyright (c) 1998-2002,2004,2006-2013 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.)
  *