title: ERROR: Error installing ffi: ERROR: Failed to build gem native extension
body: <p>I am getting this error in Mac 64 bit and have xcode inatalled on machine.</p>
  
  <pre><code>Building native extensions.  This could take a while...
  ERROR:  Error installing ffi:
      ERROR: Failed to build gem native extension.
  
  /Users/jreddy/.rvm/rubies/ruby-1.8.7-p302/bin/ruby extconf.rb
  checking for ffi.h in /usr/local/include... no
  checking for rb_thread_blocking_region()... no
  checking for ruby_thread_has_gvl_p()... no
  checking for ruby_native_thread_p()... no
  checking for rb_thread_call_with_gvl()... no
  creating extconf.h
  creating Makefile
  
  make
  sh: make: command not found
  </code></pre>