--- pdfium/third_party/zlib_v1211/zconf.h	2017-03-27 09:56:51.172107336 -0700
+++ zlib/zconf.h	2017-03-30 12:48:48.436229238 -0700
@@ -431,7 +431,7 @@
    typedef unsigned long z_crc_t;
 #endif

-#ifdef HAVE_UNISTD_H    /* may be set to #if 1 by ./configure */
+#if !defined(_WIN32)
 #  define Z_HAVE_UNISTD_H
 #endif