* ext/win32/lib/Win32API.rb: Fiddle::Importer is defined in
  fiddle/import.rb and it's not loaded implicitly.

* ext/win32/lib/Win32API.rb (Win32API#initialize): `import` is a string.

* ext/win32/lib/Win32API.rb (Win32API#initialize):
  Fiddle::Importer::CALL_TYPE_TO_ABI is private constant.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@48270 b2dd03c8-39d4-4d8f-98ff-823fe69b080e