(PUP-2521) Remove Ruby 1.9.3 windows-pr gem +deps

 - With our gemset being FFI based, we no longer need to rely on
   windows-pr gem.  That also removes the need for the windows-apii and
   win32-api gems.
Merge remote-tracking branch 'ethan/ticket/1.9.3-x86/PUP-2521-remove-windows-pr-gem' into 1.9.3-x86

* ethan/ticket/1.9.3-x86/PUP-2521-remove-windows-pr-gem:
  (PUP-2521) Remove Ruby 1.9.3 windows-pr gem +deps