Fix build on VS2015 Update 3

Author: nba0cschuette

ICSharpCode.SharpZipLib/ICSharpCode.SharpZipLib.csproj

@@ -1,5 +1,6 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003" xmlns:Conversion="urn:Conversion" ToolsVersion="12.0">
+  <Import Project="$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props" Condition="Exists('$(MSBuildExtensionsPath)\$(MSBuildToolsVersion)\Microsoft.Common.props')" />
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Release</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">AnyCPU</Platform>