Copy support for C++ native from 1.2.10

Issue Description

In an empty C++ project, when trying to install any NuGet version except 1.2.10, we get an error:

Severity Code Description Project File Line Suppression State
Error Could not install package 'log4net 2.0.8'. You are trying to install this package into a project that targets 'native,Version=v0.0', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.

But, it does work when installing log4net 1.2.10.

Steps to reproduce

• Create empty C++ project in Visual Studio
• Right click on the project -> manage NuGet packages.
• Search for Log4Net, choose any of the affected version -> Install

 Tested on Visual Studio 2017 (15.9.3)

Possible solution

• see https://stackoverflow.com/a/35068273/426315

I tried to realize why does it work with 1.2.10 but I couldn't find anything in the related branch in github (_1.2.10-RC2)

I guess it was a change done on the machine that built the version before uploading to NuGet, and was not committed into the repository.