Add missing [PreserveSig] to a couple ISymUnmanagedScope members...

src/Dependencies/Microsoft.DiaSymReader/ISymUnmanagedScope.cs

@@ -11,8 +11,10 @@ namespace Microsoft.DiaSymReader
     [ComVisible(false)]
     public interface ISymUnmanagedScope
     {
+        [PreserveSig]
         int GetMethod([MarshalAs(UnmanagedType.Interface)] out ISymUnmanagedMethod method);
 
+        [PreserveSig]
         int GetParent([MarshalAs(UnmanagedType.Interface)] out ISymUnmanagedScope scope);
 
         [PreserveSig]

src/Dependencies/Microsoft.DiaSymReader/ISymUnmanagedScope2.cs

@@ -13,8 +13,10 @@ public interface ISymUnmanagedScope2 : ISymUnmanagedScope
     {
         #region ISymUnmanagedScope methods 
 
+        [PreserveSig]
         new int GetMethod([MarshalAs(UnmanagedType.Interface)] out ISymUnmanagedMethod method);
 
+        [PreserveSig]
         new int GetParent([MarshalAs(UnmanagedType.Interface)] out ISymUnmanagedScope scope);
 
         [PreserveSig]