Revert of Removing #defines previously used for building without BoringSSL/OpenSSL.

webrtc/base/openssladapter.cc

 /*
  *  Copyright 2008 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.
  */
 
+#if HAVE_OPENSSL_SSL_H
+
 #include "webrtc/base/openssladapter.h"
 
 #if defined(WEBRTC_POSIX)
 #include <unistd.h>
 #endif
 
 // Must be included first before openssl headers.
 #include "webrtc/base/win32.h"  // NOLINT
 
 #include <openssl/bio.h>
@@ skipping 935 matching lines @@
   SSL_CTX_set_cipher_list(ctx, "ALL:!ADH:!LOW:!EXP:!MD5:@STRENGTH");
 
   if (ssl_mode_ == SSL_MODE_DTLS) {
     SSL_CTX_set_read_ahead(ctx, 1);
   }
 
   return ctx;
 }
 
 } // namespace rtc
+
+#endif  // HAVE_OPENSSL_SSL_H