Cleanup unused usings.

Mono.Net.Security/LegacySslStream.cs is the only file which should
reference the 'Mono.Security.Protocol.Tls' namespace.

(cherry picked from commit 43307ff08684e6889bc24976cb128216e82b7179)

mcs/class/System/Mono.Net.Security/MonoDefaultTlsProvider.cs

@@ -43,10 +43,8 @@ using XX509CertificateCollection = System.Security.Cryptography.X509Certificates
 
 #if MONO_SECURITY_ALIAS
 using MonoSecurity::Mono.Security.Interface;
-using MonoSecurity::Mono.Security.Protocol.Tls;
 #else
 using Mono.Security.Interface;
-using Mono.Security.Protocol.Tls;
 #endif
 
 using System;

mcs/class/System/Mono.Net.Security/MonoSslStreamWrapper.cs

@@ -34,19 +34,9 @@ extern alias MonoSecurity;
 #endif
 
 #if MONO_SECURITY_ALIAS
-using MonoCipherAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.CipherAlgorithmType;
-using MonoHashAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.HashAlgorithmType;
-using MonoExchangeAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.ExchangeAlgorithmType;
-using MonoSecurityProtocolType = MonoSecurity::Mono.Security.Protocol.Tls.SecurityProtocolType;
 using MonoSecurity::Mono.Security.Interface;
-// using MonoSecurity::Mono.Security.Protocol.Tls;
 #else
-using MonoCipherAlgorithmType = Mono.Security.Protocol.Tls.CipherAlgorithmType;
-using MonoHashAlgorithmType = Mono.Security.Protocol.Tls.HashAlgorithmType;
-using MonoExchangeAlgorithmType = Mono.Security.Protocol.Tls.ExchangeAlgorithmType;
-using MonoSecurityProtocolType = Mono.Security.Protocol.Tls.SecurityProtocolType;
 using Mono.Security.Interface;
-// using Mono.Security.Protocol.Tls;
 #endif
 #if MONO_X509_ALIAS
 using XSslProtocols = PrebuiltSystem::System.Security.Authentication.SslProtocols;

mcs/class/System/System.Net.Security/SslStream.cs

@@ -34,19 +34,9 @@ extern alias MonoSecurity;
 #endif
 
 #if MONO_SECURITY_ALIAS
-using MonoCipherAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.CipherAlgorithmType;
-using MonoHashAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.HashAlgorithmType;
-using MonoExchangeAlgorithmType = MonoSecurity::Mono.Security.Protocol.Tls.ExchangeAlgorithmType;
-using MonoSecurityProtocolType = MonoSecurity::Mono.Security.Protocol.Tls.SecurityProtocolType;
 using MonoSecurity::Mono.Security.Interface;
-// using MonoSecurity::Mono.Security.Protocol.Tls;
 #else
-using MonoCipherAlgorithmType = Mono.Security.Protocol.Tls.CipherAlgorithmType;
-using MonoHashAlgorithmType = Mono.Security.Protocol.Tls.HashAlgorithmType;
-using MonoExchangeAlgorithmType = Mono.Security.Protocol.Tls.ExchangeAlgorithmType;
-using MonoSecurityProtocolType = Mono.Security.Protocol.Tls.SecurityProtocolType;
 using Mono.Security.Interface;
-// using Mono.Security.Protocol.Tls;
 #endif
 #if MONO_X509_ALIAS
 using XSslProtocols = PrebuiltSystem::System.Security.Authentication.SslProtocols;

mcs/class/System/System.Net/HttpListenerRequest.cs

@@ -30,13 +30,6 @@
 
 #if SECURITY_DEP
 
-#if MONOTOUCH || MONODROID
-using Mono.Security.Protocol.Tls;
-#else
-extern alias MonoSecurity;
-using MonoSecurity::Mono.Security.Protocol.Tls;
-#endif
-
 using System.Collections;
 using System.Collections.Specialized;
 using System.Globalization;