Backport fix:
Use the following method to determine the status message to
be displayed (the term "contact" should be read as
"contact of the metacontact" and "online" as "not offline"):
* Display the new status message if
- the new status message is not empty and
- the contact who set it is online or there are no contacts online at all.
* Otherwise display the first non-empty status message among all contacts
online---or offline if there are no contacts online at all.
* If no status message is displayed yet display no status message at all.

CCBUG: 116614