Component: Microsoft.Wpf.Interop.DirectX.dll should have TargetFrameworkVersionAttribute=4.5

[rrelyea]

The DLL we created is usually used from NuGet which properly says it works in 4.5 and later.
We should also make sure that the DLL has TargetFrameworkVersionAttribute.

Recently we moved from 2 assemblies, into 1. This broke during that change.