Duplicate keys added when populating reference assemblies on mono

[davidfowl]

See davidfowl/HelloWorldVNext#1

https://github.com/aspnet/KRuntime/blob/dev/src/Microsoft.Framework.Runtime/FrameworkReferenceResolver.cs#L112

[xplicit]

Issue is closed, but just some additional info.

I added a printing of keys and values in the Dictionary.Add method, here are part of the output. There are two libraries System.Windows.dll in the '4.5' dir and in the '4.5/Facades' dir

key=System.Windows value=/usr/lib/mono/4.5/System.Windows.dll
key=WindowsBase value=/usr/lib/mono/4.5/WindowsBase.dll
key=System.Runtime.InteropServices.WindowsRuntime value=/usr/lib/mono/4.5/Facades/System.Runtime.InteropServices.WindowsRuntime.dll
key=System.Windows value=/usr/lib/mono/4.5/Facades/System.Windows.dll

[davidfowl]

@xplicit thanks. I've updated the logic to just overwrites entries. It should just work fine. KRE 471 should have it.