Fix Ansible provisioner exit code reporting

In eb70c0d6bb we were trying to compare a Subprocess::Result to a
Fixnum, resulting in Vagrant always reporting failure regardless of
Ansible's exit code.

plugins/provisioners/ansible/provisioner.rb

@@ -31,13 +31,13 @@ module VagrantPlugins
         }
 
         begin
-          exit_status = Vagrant::Util::Subprocess.execute(*command) do |type, data|
+          result = Vagrant::Util::Subprocess.execute(*command) do |type, data|
             if type == :stdout || type == :stderr
               @machine.env.ui.info(data, :new_line => false, :prefix => false)
             end
           end
 
-          raise Vagrant::Errors::AnsibleFailed if exit_status != 0
+          raise Vagrant::Errors::AnsibleFailed if result.exit_code != 0
         rescue Vagrant::Util::Subprocess::LaunchError
           raise Vagrant::Errors::AnsiblePlaybookAppNotFound
         end