* Fill in undefined var in `Tests_Option_BlogOption`
* Add `defined()` check for `BLOGSUPLOADDIR`
* Suppress deprecated function notices for `is_blog_user()` and `get_dashboard_blog()`
* Check existence of `$user` in `wpmu_log_new_registrations()` before arbitrarily making a database query

Fixes all notices in multisite unit tests.

See #25282.



git-svn-id: https://develop.svn.wordpress.org/trunk@25397 602fd350-edb4-49c9-b593-d223f7449a82