Fallback to powershell implementation under the bundle environment

[Bug #21645]

win32-registory can't load fiddle if Gemfile didn't have that dependency.

Author: hsbt

ext/win32/resolv/lib/resolv.rb

@@ -58,7 +58,7 @@ def read_s(key)
         end
       end
       using SZ
-    rescue LoadError
+    rescue LoadError, Gem::LoadError
       require "open3"
     end