contrib: Patch libpng to make it build with automake 1.12 and 1.11 again

contrib/src/png/automake.patch

+diff -ur png/configure.ac png.new/configure.ac
+--- png/configure.ac	2013-07-18 03:03:02.000000000 +0300
++++ png.new/configure.ac	2013-08-08 19:20:12.459900241 +0300
+@@ -27,7 +27,7 @@
+ # dist-xz requires automake 1.11 or later
+ # 1.12.2 fixes a security issue in 1.11.2 and 1.12.1
+ # 1.13 is required for parallel tests
+-AM_INIT_AUTOMAKE([1.13 foreign dist-xz color-tests silent-rules])
++AM_INIT_AUTOMAKE([1.11 foreign dist-xz color-tests silent-rules])
+ # The following line causes --disable-maintainer-mode to be the default to
+ # configure, this is necessary because libpng distributions cannot rely on the
+ # time stamps of the autotools generated files being correct

contrib/src/png/rules.mak

@@ -16,6 +16,7 @@ png: libpng-$(PNG_VERSION).tar.xz .sum-png
 	$(UNPACK)
 	$(APPLY) $(SRC)/png/winrt.patch
 	$(APPLY) $(SRC)/png/bins.patch
+	$(APPLY) $(SRC)/png/automake.patch
 	$(MOVE)
 
 DEPS_png = zlib $(DEPS_zlib)