title: unable to install mysql-2.9.1.gem in windows 8.1 with ruby version 2.1.5
body: <p>I am using Ruby 2.1.5 and rest details are</p>
  
  <p><strong>* LOCAL GEMS *</strong></p>
  
  <p>bigdecimal (1.2.4)
  io-console (0.4.2)
  json (1.8.1)
  minitest (4.7.5)
  mysql (2.8.1 x86-mingw32)
  psych (2.0.5)
  rake (10.1.0)
  rdoc (4.1.0)
  test-unit (2.1.5.0)</p>
  
  <p>and when i am installing mysql-2.9.1.gem it is giving an error as follows::</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing mysql-2.9.1.gem:
          ERROR: Failed to build gem native extension.
  
      C:/Ruby21-x64/bin/ruby.exe extconf.rb
  checking for main() in -llibmysql... *** 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-x64/bin/ruby
          --with-mysql-dir
          --without-mysql-dir
          --with-mysql-include
          --without-mysql-include=${mysql-dir}/include
          --with-mysql-lib
          --without-mysql-lib=${mysql-dir}/lib
          --with-libmysqllib
          --without-libmysqllib
  C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:456:in `try_do': The compiler failed to gen
  erate an executable file. (RuntimeError)
  You have to install development tools first.
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:541:in `try_link0'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:556:in `try_link'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:742:in `try_func'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:973:in `block in have_library'
  
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:918:in `block in checking_for'
  
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:351:in `block (2 levels) in po
  stpone'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:321:in `open'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:351:in `block in postpone'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:321:in `open'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:347:in `postpone'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:917:in `checking_for'
          from C:/Ruby21-x64/lib/ruby/2.1.0/mkmf.rb:968:in `have_library'
          from extconf.rb:27:in `&lt;main&gt;'
  
  extconf failed, exit code 1
  
  Gem files will remain installed in C:/Ruby21-x64/lib/ruby/gems/2.1.0/gems/mysql-
  2.9.1 for inspection.
  Results logged to C:/Ruby21-x64/lib/ruby/gems/2.1.0/extensions/x64-mingw32/2.1.0
  /mysql-2.9.1/gem_make.out
  
  D:\Softwares&gt;
  </code></pre>