Update zlib to 1.2.5.

third_party/zlib/inffast.h

Index: third_party/zlib/inffast.h
===================================================================
--- third_party/zlib/inffast.h	(revision 112951)
+++ third_party/zlib/inffast.h	(working copy)
@@ -1,5 +1,5 @@
 /* inffast.h -- header to use inffast.c
- * Copyright (C) 1995-2003 Mark Adler
+ * Copyright (C) 1995-2003, 2010 Mark Adler
  * For conditions of distribution and use, see copyright notice in zlib.h
  */
 
@@ -8,4 +8,4 @@
    subject to change. Applications should only use zlib.h.
  */
 
-void inflate_fast OF((z_streamp strm, unsigned start));
+void ZLIB_INTERNAL inflate_fast OF((z_streamp strm, unsigned start));