Fix missing linked file ReadOnlyStream

Added ReadOnlyStream to the compile includes for the Client project.

Author: mizady

nanoFramework.System.Net.Http.Client/System.Net.Http.Client.nfproj

@@ -105,6 +105,7 @@
     <Compile Include="..\nanoFramework.System.Net.Http\Http\HttpResponseMessage.cs">
       <Link>Http\HttpResponseMessage.cs</Link>
     </Compile>
+    <Compile Include="..\nanoFramework.System.Net.Http\Http\ReadOnlyStream.cs" Link="Http\ReadOnlyStream.cs" />
     <Compile Include="..\nanoFramework.System.Net.Http\Http\StreamContent.cs">
       <Link>Http\StreamContent.cs</Link>
     </Compile>