The Mac build requires some content be pulled from nuget.org, see https://github.com/dotnet/corefx/issues/2236; this change adds it to the source list passed to nuget.exe.

[tfs-changeset: 1499319]

Author: jhendrixMSFT

dir.props

@@ -45,7 +45,8 @@
 
   <!-- list of nuget package sources passed to nuget.exe -->
   <ItemGroup>
-    <NuGetSourceList Include="https://www.myget.org/F/dotnet-buildtools" />
+    <NuGetSourceList Include="https:%2F%2Fwww.myget.org/F/dotnet-buildtools" />
+    <NuGetSourceList Include="https:%2F%2Fwww.nuget.org/api/v2" />
   </ItemGroup>
 
   <!-- Common nuget properties -->