Remove HAVE_SRTP define and unmaintained code.

webrtc/pc/externalhmac.cc

 /*
  *  Copyright 2014 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.
  */
 
 #include "webrtc/pc/externalhmac.h"
 
 #include <stdlib.h>  // For malloc/free.
 
 #include "webrtc/base/logging.h"
 
-#ifdef HAVE_SRTP
 #include "third_party/libsrtp/crypto/include/crypto_kernel.h"
 #include "third_party/libsrtp/include/srtp.h"
-#endif // HAVE_SRTP
-
-#if defined(HAVE_SRTP)
 
 // Begin test case 0 */
 static const uint8_t kExternalHmacTestCase0Key[20] = {
   0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
   0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b, 0x0b,
   0x0b, 0x0b, 0x0b, 0x0b
 };
 
 static const uint8_t kExternalHmacTestCase0Data[8] = {
   0x48, 0x69, 0x20, 0x54, 0x68, 0x65, 0x72, 0x65   // "Hi There"
@@ skipping 110 matching lines @@
   // non-const.
   srtp_err_status_t status = srtp_replace_auth_type(
       const_cast<srtp_auth_type_t*>(&external_hmac), EXTERNAL_HMAC_SHA1);
   if (status) {
     LOG(LS_ERROR) << "Error in replacing default auth module, error: "
                   << status;
     return srtp_err_status_fail;
   }
   return srtp_err_status_ok;
 }
-
-#endif  // defined(HAVE_SRTP)