title: therubyracer installation on windows with libv8 installed --with-system-v8
body: <p>I finally got libv8 installed on my windows with 
  gem install libv8 -- --with-system-v8</p>
  
  <p>now when I am trying to install therubyracer I get </p>
  
  <pre><code>gem install therubyracer
  Temporarily enhancing PATH to include DevKit...
  Building native extensions.  This could take a while...
  Building native extensions.  This could take a while...
  ERROR:  Error installing therubyracer:
          ERROR: Failed to build gem native extension.
  
          C:/Ruby193/bin/ruby.exe extconf.rb --with-system-v8
  checking for main() in -lpthread... no
  checking for v8.h... no
  *** 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:/Ruby193/bin/ruby
          --with-pthreadlib
          --without-pthreadlib
          --enable-debug
          --disable-debug
          --with-v8-dir
          --without-v8-dir
          --with-v8-include
          --without-v8-include=${v8-dir}/include
          --with-v8-lib
          --without-v8-lib=${v8-dir}/
  C:/Ruby193/lib/ruby/gems/1.9.1/gems/libv8-3.16.14.3/ext/libv8/location.rb:50:in `configure': You hav
  e chosen to use the version of V8 found on your system (Libv8::Location::System::NotFoundError)
  and *not* the one that is bundle with the libv8 rubygem. However,
  it could not be located. please make sure you have a version of
  v8 that is compatible with 3.16.14.3 installed. You may
  need to special --with-v8-dir options if it is in a non-standard
  location
  
  thanks,
  The Mgmt
  </code></pre>
  
  <p>What I want to know is what this error message really means?
  Also I looked this up <a href="https://github.com/cowboyd/libv8#bring-your-own-v8" rel="nofollow">https://github.com/cowboyd/libv8#bring-your-own-v8</a>
  How do I install headers for v8?</p>