GN: Suppress MSVC "const should be initialized" warning in NaCl code

build/config/nacl/BUILD.gn

 # Copyright (c) 2014 The Native Client Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/nacl/config.gni")
 
 # Native Client Definitions
 config("nacl_defines") {
   if (is_linux || is_android || is_nacl) {
     defines = [
       "_POSIX_C_SOURCE=199506",
       "_XOPEN_SOURCE=600",
       "_GNU_SOURCE=1",
       "__STDC_LIMIT_MACROS=1",
     ]
   } else if (is_win) {
     defines = [ "__STDC_LIMIT_MACROS=1" ]
   }
 }
 
 config("nexe_defines") {
   defines = [
     "DYNAMIC_ANNOTATIONS_ENABLED=1",
     "DYNAMIC_ANNOTATIONS_PREFIX=NACL_",
   ]
 }
 
+config("nacl_warnings") {
+  if (is_win) {
+    # Some NaCl code uses forward declarations of static const variables,
+    # with initialized definitions later on.  (The alternative would be
+    # many, many more forward declarations of everything used in that
+    # const variable's initializer before the definition.)  The Windows
+    # compiler is too stupid to notice that there is an initializer later
+    # in the file, and warns about the forward declaration.
+    cflags = [ "/wd4132" ]
+  }
+}
+
 # The base target that all targets in the NaCl build should depend on.
 # This allows configs to be modified for everything in the NaCl build, even when
 # the NaCl build is composed into the Chrome build.  (GN has no functionality to
-# add flags to everythin in //native_client, having a base target works around
+# add flags to everything in //native_client, having a base target works around
 # that limitation.)
 source_set("nacl_base") {
-  public_configs = [ ":nacl_defines" ]
+  public_configs = [
+    ":nacl_defines",
+    ":nacl_warnings",
+  ]
   if (current_os == "nacl") {
     public_configs += [ ":nexe_defines" ]
   }
 }
 
 config("compiler") {
   configs = []
   cflags = []
   ldflags = []
   libs = []
@@ skipping 68 matching lines @@
     "-Os",
 
     # These are omitted from non-IRT libraries to keep the libraries
     # themselves small.
     "-ffunction-sections",
     "-fdata-sections",
   ]
 
   ldflags = [ "-Wl,--gc-sections" ]
 }