[corlib] Move ComAwareEventInfo stub into System.Core

It was mistakenly added to corlib, it is in System.Core.dll on .NET

mcs/class/System.Core/common_System.Core.dll.sources

@@ -229,6 +229,8 @@ ReferenceSources/Strings.cs
 
 ../referencesource/System.Core/System/threading/Tasks/TaskExtensions.cs
 
+System.Runtime.InteropServices/ComAwareEventInfo.cs
+
 System.Security.Cryptography/ECCurve.cs
 System.Security.Cryptography/ECPoint.cs
 System.Security.Cryptography/ECParameters.cs

mcs/class/corlib/corlib.dll.sources

@@ -421,7 +421,6 @@ System.Runtime.InteropServices/UCOMITypeLib.cs
 System.Runtime.InteropServices/VARDESC.cs
 System.Runtime.InteropServices/VARFLAGS.cs
 System.Runtime.InteropServices/CustomQueryInterfaceMode.cs
-System.Runtime.InteropServices/ComAwareEventInfo.cs
 System.Runtime.InteropServices/ComEventsHelper.cs
 
 System.Runtime.InteropServices.WindowsRuntime/DesignerNamespaceResolveEventArgs.cs