Multiple "Attempt to modify property of non-object in antispam_prepare_comment_data()" warnings

When calling the method antispam_api_cmd_spam_check(), a "content" array is created any passed to the method antispam_api_cmd_comment_check(). However, antispam_api_cmd_comment_check() expects and object, not an array.

The following patch first casts the array as an object before passing it to antispam_api_cmd_comment_check().

Cheers,
Chris