title: debugger gem installation issue on windows 7
body: <p>Not able to install <code>debugger</code> or <code>ruby-debug19</code> on a windows 64 bit machine. Have installed Devkit, rubygems and able to install all the other gems except this. </p>
  
  <pre><code>ruby -v 
  ruby 1.9.3p551 (2014-11-13) [i386-mingw32]
  
  gem --version
  2.4.1
  </code></pre>
  
  <p><strong>ERROR :</strong> </p>
  
  <pre><code>gem install debugger
  Temporarily enhancing PATH to include DevKit...
  Building native extensions.  This could take a while...
  ERROR:  Error installing debugger:
          ERROR: Failed to build gem native extension.
  
      C:/Ruby193/bin/ruby.exe -r ./siteconf20141205-5484-1qgupo8.rb extconf.rb
  
  
   checking for rb_method_entry_t.called_id in method.h... no
      checking for rb_control_frame_t.method_id in method.h... no
      checking for rb_method_entry_t.called_id in method.h... yes
      checking for vm_core.h... yes
      checking for iseq.h... yes
      checking for insns.inc... yes
      checking for insns_info.inc... yes
      checking for eval_intern.h... yes
      checking for struct iseq_line_info_entry in vm_core.h,iseq.h... no
      checking for struct iseq_insn_info_entry in vm_core.h,iseq.h... yes
      checking for if rb_iseq_compile_with_option was added an argument filepath... yes
      creating Makefile
  
      make  clean
      Makefile:165: *** target pattern contains no `%'.  Stop.
  
      make
      Makefile:165: *** target pattern contains no `%'.  Stop.
  
      make failed, exit code 2
  
      Gem files will remain installed in C:/Ruby193/lib/ruby/gems/1.9.1/gems/debugger-1.6.8 for inspection.
      Results logged to C:/Ruby193/lib/ruby/gems/1.9.1/extensions/x86-mingw32/1.9.1/debugger-1.6.8/gem_make.out
  
  gem list
  
  *** LOCAL GEMS ***
  
  archive-tar-minitar (0.5.2)
  atk (2.2.3 x86-mingw32)
  bigdecimal (1.1.0)
  cairo (1.14.0 x86-mingw32)
  columnize (0.8.9)
  debugger-linecache (1.2.0)
  debugger-ruby_core_source (1.3.7, 1.1.6
  gdk_pixbuf2 (2.2.3 x86-mingw32)
  glib2 (2.2.3 x86-mingw32)
  green_shoes (1.1.374)
  gtk2 (2.2.3 x86-mingw32)
  io-console (0.3)
  json (1.5.5)
  minitest (2.5.1)
  pango (2.2.3 x86-mingw32)
  pkg-config (1.1.6)
  rake (0.9.2.2)
  rbx-require-relative (0.0.9)
  rdoc (3.9.5)
  ruby_core_source (0.1.5)
  rubygems-update (2.4.5)
  </code></pre>
  
  <p>Thanks in advance</p>