Reland "C++ porting of the initial python script for conversational speech generation."

webrtc/modules/audio_processing/test/conversational_speech/BUILD.gn

+# Copyright (c) 2017 The WebRTC project authors. All Rights Reserved.
+#
+# Use of this source code is governed by a BSD-style license
+# that can be found in the LICENSE file in the root of the source
+# tree. An additional intellectual property rights grant can be found
+# in the file PATENTS.  All contributing project authors may
+# be found in the AUTHORS file in the root of the source tree.
+
+import("../../../../webrtc.gni")
+
+group("conversational_speech") {
+  testonly = true
+  deps = [
+    ":convspeech_gen",
+  ]
+}
+
+rtc_executable("convspeech_gen") {
+  testonly = true
+  sources = [
+    "convspeech_gen.cc",
+    "settings.cc",
+    "settings.h",
+  ]
+  deps = [
+    "//third_party/gflags",
+    "//webrtc/base:rtc_base_approved",
+    "//webrtc/test:test_support",
+  ]
+  visibility = [ ":*" ]  # Only targets in this file can depend on this.
+}