Plumb use_system_xcode through native client.

src/trusted/service_runtime/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/toolchain/toolchain.gni")
 import("//native_client/src/trusted/asm.gni")
 
 source_set("sel_main") {
   sources = [
     "sel_main.c",
   ]
   deps = [
     "//build/config/nacl:nacl_base",
     "//native_client/src/trusted/debug_stub:debug_stub",
     ":sel",
@@ skipping 304 matching lines @@
     script = "osx/run_mig.py"
     sources = [
       mac_sdk_path + "/usr/include/mach/exc.defs",
     ]
     outputs = [
       "$target_gen_dir/nacl_exc.h",
       "$target_gen_dir/nacl_exc_server.c",
     ]
     args = rebase_path(sources, root_build_dir) +
            rebase_path(outputs, root_build_dir)
+    if (!use_system_xcode) {
+      args += [ hermetic_xcode_path]

[bradnelson, 2016/10/13 20:58:22]

spacing on the right is funny.

[erikchen, 2016/10/13 21:11:40]

Done.

+    }
   }
 }
 
 executable("sel_ldr") {
   sources = [
     "nacl_test_injection_main.c",
   ]
   deps = [
     ":sel_main",
 
     # All executables must have the sanitizer deps to properly link in
     # asan mode (this target will be empty in other cases).
     "//build/config/sanitizers:deps",
 
     "//build/win:default_exe_manifest",
   ]
   if (is_linux) {
     configs -= [ "//build/config:default_libs" ]
     libs = [ "rt" ]
     ldflags = [ "-pie" ]
   }
   if (is_linux) {
     data_deps = [
       "linux:bootstrap",
     ]
   }
 }