Remove code interfacing legacy openssl.

BUG=

Review URL: https://codereview.webrtc.org/1808763002

Cr-Commit-Position: refs/heads/master@{#12041}

webrtc/base/openssladapter.h

@@ -27,8 +27,6 @@ namespace rtc {
 class OpenSSLAdapter : public SSLAdapter, public MessageHandler {
 public:
   static bool InitializeSSL(VerificationCallback callback);
-  static bool InitializeSSLThread();
-  static bool CleanupSSL();
 
   OpenSSLAdapter(AsyncSocket* socket);
   ~OpenSSLAdapter() override;