get_blog_option doesn't return new value once the same option is updated with update_option

[mohanjith]

Once a blog option is cached into object cache any updates to the same option made with update_option() are not propagated unless the cache expires or is removed by other means.

In the attached patch I hook onto updated_option action and update the option cached into site-options group and also calls refresh_blog_details($wpdb->blogid) if the updated option concerns blog details (Only for 'blogname','siteurl','post_count').

[SergeyBiryukov]

#15548