Contribs: update libpng to 1.6.3

contrib/src/png/SHA512SUMS

-6f4bfd143a56c56f7ab61475b09123fe33cde95a63bc3f1f0756f708670b1a6e915c2891833e44546a18ff1254099ddf34f33d5e13cd8a61842ec53b179904e4  libpng-1.5.17.tar.bz2
+a720e1b576958a445ccf301c3de2dbf1ea58590c23ec4edd76ee1d65ab611c941b82e173fbef1974c5efbe8bf31d8e800e34f37819d9f406db4ef704d12106df  libpng-1.6.3.tar.xz

contrib/src/png/automake.patch

-diff -ur png/configure.ac png.new/configure.ac
---- png/configure.ac	2013-06-27 06:25:42.000000000 +0300
-+++ png.new/configure.ac	2013-07-09 14:19:02.953919579 +0300
-@@ -19,7 +19,7 @@
- dnl Version number stuff here:
- 
- AC_INIT([libpng], [1.5.17], [png-mng-implement@lists.sourceforge.net])
--AM_INIT_AUTOMAKE([serial-tests])
-+AM_INIT_AUTOMAKE
- dnl stop configure from automagically running automake
- AM_MAINTAINER_MODE
- 

contrib/src/png/rules.mak

 # PNG
-PNG_VERSION := 1.5.17
-PNG_URL := $(SF)/libpng/libpng-$(PNG_VERSION).tar.bz2
+PNG_VERSION := 1.6.3
+PNG_URL := $(SF)/libpng/libpng16/$(PNG_VERSION)/libpng-$(PNG_VERSION).tar.xz
 
 PKGS += png
 ifeq ($(call need_pkg,"libpng"),)
 PKGS_FOUND += png
 endif
 
-$(TARBALLS)/libpng-$(PNG_VERSION).tar.bz2:
+$(TARBALLS)/libpng-$(PNG_VERSION).tar.xz:
 	$(call download,$(PNG_URL))
 
-.sum-png: libpng-$(PNG_VERSION).tar.bz2
+.sum-png: libpng-$(PNG_VERSION).tar.xz
 
-png: libpng-$(PNG_VERSION).tar.bz2 .sum-png
+png: libpng-$(PNG_VERSION).tar.xz .sum-png
 	$(UNPACK)
 	$(APPLY) $(SRC)/png/winrt.patch
-	$(APPLY) $(SRC)/png/automake.patch
 	$(MOVE)
 
 DEPS_png = zlib $(DEPS_zlib)

contrib/src/png/winrt.patch

@@ -12,12 +12,3 @@
  #endif
  
  #ifdef USE_FAR_KEYWORD
-@@ -381,7 +377,7 @@
- #  ifdef _WINDOWS_  /* Favor Windows over C runtime fns */
- #    define CVT_PTR(ptr)         (ptr)
- #    define CVT_PTR_NOCHECK(ptr) (ptr)
--#    define png_strlen  lstrlenA
-+#    define png_strlen  strlen
- #    define png_memcmp  memcmp
- #    define png_memcpy  CopyMemory
- #    define png_memset  memset