Build nacl_helper_nonsfi with GN

ipc/BUILD.gn

Index: ipc/BUILD.gn
diff --git a/ipc/BUILD.gn b/ipc/BUILD.gn
index 44917eea473774ce0cc28cb932dc5568adf902e2..fdd0a764debf3d75cb92fde74c8ce6e73ae87b9c 100644
--- a/ipc/BUILD.gn
+++ b/ipc/BUILD.gn
@@ -2,6 +2,7 @@
 # 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")
 import("//testing/test.gni")
 
 component("ipc") {
@@ -117,6 +118,17 @@ component("ipc") {
     sources -= [ "unix_domain_socket_util.cc" ]
   }
 
+  if (is_nacl_nonsfi) {
+    sources -= [
+      "ipc_channel_nacl.cc",
+      "ipc_channel_nacl.h",
+    ]
+    sources += [
+      "ipc_channel.cc",
+      "ipc_channel_posix.cc",
+    ]
+  }
+
   defines = [ "IPC_IMPLEMENTATION" ]
 
   deps = [