dvdauthor: fix compiling against libpng 1.5.x

DVDAuthor on Lion suffers from the same issue as Gentoo appears to
(https://bugs.gentoo.org/355039?id=355039) with libpng 1.5.x. Add
an explicit reference to zlib.h, and fix dereferencing of pointer
to incomplete type.

Signed-off-by: Adam Vandenberg <flangy@gmail.com>

Formula/dvdauthor.rb

@@ -11,6 +11,10 @@ class Dvdauthor < Formula
   depends_on 'pkg-config' => :build
   depends_on 'libdvdread'
 
+  def patches
+    { :p0 => DATA }
+  end
+
   def install
     ENV.x11 # For libpng, etc.
     system "./configure", "--disable-dependency-tracking",
@@ -21,3 +25,27 @@ class Dvdauthor < Formula
     system "make install"
   end
 end
+
+__END__
+http://bugs.gentoo.org/355039
+Fix build with png-1.5.
+
+--- src/spuunmux.c.orig	2010-05-10 11:27:55.000000000 +0400
++++ src/spuunmux.c	2011-03-17 11:20:25.000000000 +0300
+@@ -39,6 +39,7 @@
+ #include <netinet/in.h>
+ 
+ #include <png.h>
++#include <zlib.h>
+ 
+ #include "rgb.h"
+ #include "common.h"
+@@ -610,7 +611,7 @@
+         png_destroy_write_struct(&png_ptr, (png_infopp)NULL);
+         return -1;
+       } /*if*/
+-    if (setjmp(png_ptr->jmpbuf))
++    if (setjmp(png_jmpbuf(png_ptr)))
+       {
+         png_destroy_write_struct(&png_ptr, &info_ptr);
+         fclose(fp);