Fix build error in xamarin.

Author: yfakariya

src/MsgPack/Serialization/MessagePackSerializer.cs

@@ -212,15 +212,15 @@ internal static MessagePackSerializer<T> CreateInternal<T>( SerializationContext
 			Contract.Ensures( Contract.Result<MessagePackSerializer<T>>() != null );
 #endif // !XAMIOS && !XAMDROID && !UNITY
 
-#if DEBUG && !UNITY
+#if DEBUG && !UNITY && !XAMDROID && !XAMIOS
 			SerializerDebugging.TraceEvent(
 				"SerializationContext::CreateInternal<{0}>(@{1}, {2})",
 				typeof( T ),
 				context.GetHashCode(),
 				schema == null ? "null" : schema.DebugString
 			);
 
-#endif // DEBUG && !UNITY
+#endif // DEBUG && !UNITY && !XAMDROID && !XAMIOS
 			Type concreteType = null;
 
 			if ( typeof( T ).GetIsAbstract() || typeof( T ).GetIsInterface() )

src/MsgPack/Serialization/PolymorphismSchema.Internals.cs

@@ -95,9 +95,7 @@ partial class PolymorphismSchema
 		///		ForPolymorphicTuple( Type targetType, PolymorphismSchema[] itemSchemaList )
 		/// </summary>
 		internal static readonly MethodInfo ForPolymorphicTupleMethod =
-			FromExpression.ToMethod(
-				( Type targetType, PolymorphismSchema[] itemSchemaList ) => ForPolymorphicTuple( targetType, itemSchemaList )
-			);
+			typeof( PolymorphismSchema ).GetMethod( "ForPolymorphicTuple", new[] { typeof( Type ), typeof( PolymorphismSchema[]) } );
 #endif // !WINDOWS_PHONE && !NETFX_35 && !UNITY
 
 		internal static readonly ConstructorInfo CodeTypeMapConstructor =