如何在Windows上安装gokogiri？

I'm trying to install gokogiri on Windows 8 machine, and these are steps that I have done so far :

• Download pkg-config_0.26-1_win32.zip from here, unzip/extract, and add the bin folder to path environment variable

• Donwload libxml2-2.9.2-win32-x86.7z from here, unzip to a location which path doesn't contain space(s) (otherwise gcc won't be able to find the location). Create new environment variable PKG_CONFIG_PATH, and add libxml's \lib\pkgconfig folder location to the env variable.

• Donwload and install tdm64-gcc from here

• run the following command (as suggested in the GitHub link above) : go get github.com/moovweb/gokogiri

but then I get this error :

What is the error message complaining about now? If I need to download icnov manually, how then I put it together with libxml2 to work properly?