Work on Mac GN build

tools/gn/secondary/third_party/zlib/BUILD.gn

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 config("zlib_config") {
   include_dirs = [ "." ]
 }
 
 static_library("zlib") {
   if (!is_win) {
@@ skipping 47 matching lines @@
     "contrib/minizip/unzip.h",
     "contrib/minizip/zip.c",
     "contrib/minizip/zip.h",
   ]
 
   if (!is_win) {
     sources -= [
       "contrib/minizip/iowin32.c",
       "contrib/minizip/iowin32.h",
     ]
-  } else if (is_mac || is_ios || is_android) {
+  }
+  if (is_mac || is_ios || is_android) {
     # Mac, Android and the BSDs don't have fopen64, ftello64, or fseeko64. We
     # use fopen, ftell, and fseek instead on these systems.
     defines = [ "USE_FILE32API" ]
   }
 
   if (is_clang) {
     # zlib uses `if ((a == b))` for some reason.
     cflags = [ "-Wno-parentheses-equality" ]
   }
 
@@ skipping 11 matching lines @@
     "google/zip_internal.cc",
     "google/zip_internal.h",
     "google/zip_reader.cc",
     "google/zip_reader.h",
   ]
   deps = [
     ":minizip",
     "//base",
   ]
 }