Move GN speechd target to third_party.

third_party/speech-dispatcher/BUILD.gn

+# Copyright 2014 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.
+
+import("//tools/generate_library_loader/generate_library_loader.gni")
+
+generate_library_loader("speech-dispatcher") {
+  name = "LibSpeechdLoader"
+  output_h = "libspeechd.h"
+  output_cc = "libspeechd.cc"
+  header = "<libspeechd.h>"
+  bundled_header = "\"third_party/speech-dispatcher/libspeechd.h\""
+
+  functions = [
+    "spd_open",
+    "spd_say",
+    "spd_stop",
+    "spd_close",
+    "spd_pause",
+    "spd_resume",
+    "spd_set_notification_on",
+    "spd_set_voice_rate",
+    "spd_set_voice_pitch",
+    "spd_list_synthesis_voices",
+    "spd_set_synthesis_voice",
+    "spd_list_modules",
+    "spd_set_output_module",
+  ]
+}