title: Rugged gem installation issue possibly with libgit2 on Windows
body: <p>I am using Windows and my <code>Gemfile</code> has this line:</p>
  
  <pre><code>gem 'rugged'
  </code></pre>
  
  <p>When I run <code>bundle install</code> it's giving me this error:</p>
  
  <pre><code>Installing rugged 0.21.0 with native extensions
  
  Gem::Ext::BuildError: ERROR: Failed to build gem native extension.
  
      C:/Ruby21/bin/ruby.exe extconf.rb --use-system-libraries
      checking for cmake... no 
      ERROR: CMake is required to build Rugged.
  
  *** extconf.rb failed *** Could not create Makefile due to some reason, probably lack of necessary libraries and/or headers.
  
  Check the mkmf.log file for more details. You may need configuration options.
  
  Provided configuration options:
          --with-opt-dir
          --without-opt-dir
          --with-opt-include
          --without-opt-include=${opt-dir}/include
          --with-opt-lib
          --without-opt-lib=${opt-dir}/lib
          --with-make-prog
          --without-make-prog
          --srcdir=.
          --curdir
          --ruby=C:/Ruby21/bin/ruby
  
  extconf failed, exit code 1
  
  Gem files will remain installed in
  C:/Ruby21/lib/ruby/gems/2.1.0/gems/rugged-0.21.0 for inspection.
  Results logged to C:/Ruby21/lib/ruby/gems/2.1.0/extensions/x86-mingw32/2.1.0/rugged-0.21.0/gem_make.out
  
  An error occurred while installing rugged(0.21.0), and Bundler cannot continue.
  
  Make sure that `gem install rugged -v '0.21.0'` succeeds before
  bundling.
  </code></pre>
  
  <p>I'm guessing it has something to do with <code>libgit2</code> but I'm not sure.</p>