Enable NaCl on the Linux GN x64 release build (only).

mojo/nacl/BUILD.gn

+# Copyright (c) 2015 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.
+
+# TODO(dpranke) - it's very dangerous to have files being built with one
+# toolchain having as part of the include_dirs a path to another toolchain's
+# gen/ directory; it would be easy to end up including files meant for a
+# different toolchain. We should either change this code to generate the
+# files in every toolchain, or check in the generated code. Currently
+# the plan is to do the latter.
+
 # All toolchains use the same generated code.
 gen_dir = "$root_build_dir/gen/mojo/nacl"
 
+config("mojo_nacl") {
+  include_dirs = [ "$root_build_dir/gen" ]
+}
+
 # Only allow the generator to be run by one toolchain.
 if (current_toolchain == default_toolchain) {
   # Generate the code to plumb the Mojo public API into the NaCl sandbox.
   action("mojo_nacl_codegen") {
     script = "generator/generate_nacl_bindings.py"
     args = [
       "-d",
       rebase_path(gen_dir, root_build_dir),
     ]
     inputs = [
@@ skipping 37 matching lines @@
 
 # Untrusted code
 if (is_nacl) {
   # Thunk mapping the Mojo public API onto NaCl syscalls.
   static_library("mojo") {
     sources = [
       "$gen_dir/libmojo.cc",
       "$gen_dir/mojo_irt.h",
     ]
 
-    public_configs =
-        [ "//third_party/mojo/src/mojo/public/build/config:mojo_sdk" ]
+    public_configs = [
+      ":mojo_nacl",
+      "//third_party/mojo/src/mojo/public/build/config:mojo_sdk",
+    ]
 
     public_deps = [
       ":mojo_nacl_codegen($default_toolchain)",
     ]
   }
 
   source_set("irt_mojo_sources") {
     cflags_c = [ "-std=c99" ]
     sources = [
       "$gen_dir/mojo_irt.c",
       "$gen_dir/mojo_irt.h",
     ]
+
+    public_configs = [
+      ":mojo_nacl",
+      "//third_party/mojo/src/mojo/public/build/config:mojo_sdk",
+    ]
+
     public_deps = [
       "//native_client/build/config/nacl:nacl_base",
       "//native_client/src/untrusted/irt:irt_core_lib",
       "//native_client/src/untrusted/nacl:imc_syscalls",
       ":mojo_nacl_codegen($default_toolchain)",
     ]
   }
 }