Hook up new "rtc_enable_sctp" build argument to "HAVE_SCTP" define.

webrtc/pc/BUILD.gn

 # Copyright (c) 2016 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("../build/webrtc.gni")
 
 group("pc") {
   public_deps = [
     ":rtc_pc",
   ]
 }
 
 config("rtc_pc_config") {
-  defines = [
-    "HAVE_SCTP",
-    "HAVE_SRTP",
-  ]
+  defines = [ "HAVE_SRTP" ]
+  if (rtc_enable_sctp) {
+    defines += [ "HAVE_SCTP" ]
+  }
 }
 
 rtc_static_library("rtc_pc") {
   defines = []
   sources = [
     "audiomonitor.cc",
     "audiomonitor.h",
     "bundlefilter.cc",
     "bundlefilter.h",
     "channel.cc",
@@ skipping 83 matching lines @@
 
     if (rtc_build_libsrtp) {
       deps += [ "//third_party/libsrtp" ]
     }
 
     if (is_android) {
       deps += [ "//testing/android/native_test:native_test_support" ]
     }
   }
 }