Add local suppresion for -Wparentheses and enable everywhere on Windows.

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_x86_simd") {
   if (!is_ios && (current_cpu == "x86" || current_cpu == "x64")) {
@@ skipping 84 matching lines @@
       "contrib/minizip/iowin32.c",
       "contrib/minizip/iowin32.h",
     ]
   }
   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" ]
-  }
-
   deps = [
     ":zlib",
   ]
 
+  config("minizip_warnings") {
+    if (is_clang) {
+      # zlib uses `if ((a == b))` for some reason.
+      cflags = [ "-Wno-parentheses-equality" ]
+    }
+  }
+
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
+  configs += [ ":minizip_warnings" ]
   public_configs = [ ":zlib_config" ]
 }
 
 static_library("zip") {
   sources = [
     "google/zip.cc",
     "google/zip.h",
     "google/zip_internal.cc",
     "google/zip_internal.h",
     "google/zip_reader.cc",
     "google/zip_reader.h",
   ]
   deps = [
     ":minizip",
     "//base",
   ]
 }