skip unnecesary ALPN processing on Windows (#69103)

Author: wfurt

src/libraries/System.Net.Security/src/System/Net/Security/SslStreamPal.Windows.cs

@@ -65,7 +65,7 @@ public static SecurityStatusPal AcceptSecurityContext(
             inputBuffers.SetNextBuffer(new InputSecurityBuffer(inputBuffer, SecurityBufferType.SECBUFFER_TOKEN));
             inputBuffers.SetNextBuffer(new InputSecurityBuffer(default, SecurityBufferType.SECBUFFER_EMPTY));
 
-            if (sslAuthenticationOptions.ApplicationProtocols != null && sslAuthenticationOptions.ApplicationProtocols.Count != 0)
+            if (context == null && sslAuthenticationOptions.ApplicationProtocols != null && sslAuthenticationOptions.ApplicationProtocols.Count != 0)
             {
                 byte[] alpnBytes = ConvertAlpnProtocolListToByteArray(sslAuthenticationOptions.ApplicationProtocols);
                 inputBuffers.SetNextBuffer(new InputSecurityBuffer(new ReadOnlySpan<byte>(alpnBytes), SecurityBufferType.SECBUFFER_APPLICATION_PROTOCOLS));
@@ -101,7 +101,7 @@ public static SecurityStatusPal InitializeSecurityContext(
             InputSecurityBuffers inputBuffers = default;
             inputBuffers.SetNextBuffer(new InputSecurityBuffer(inputBuffer, SecurityBufferType.SECBUFFER_TOKEN));
             inputBuffers.SetNextBuffer(new InputSecurityBuffer(default, SecurityBufferType.SECBUFFER_EMPTY));
-            if (sslAuthenticationOptions.ApplicationProtocols != null && sslAuthenticationOptions.ApplicationProtocols.Count != 0)
+            if (context == null && sslAuthenticationOptions.ApplicationProtocols != null && sslAuthenticationOptions.ApplicationProtocols.Count != 0)
             {
                 byte[] alpnBytes = ConvertAlpnProtocolListToByteArray(sslAuthenticationOptions.ApplicationProtocols);
                 inputBuffers.SetNextBuffer(new InputSecurityBuffer(new ReadOnlySpan<byte>(alpnBytes), SecurityBufferType.SECBUFFER_APPLICATION_PROTOCOLS));