The tp_cli_connection_interface_simple_presence_call_set_presence() documentation mentions that the possible values should be read from the "statuses" property. The (obscure, as usual) documentation actually means the "statuses" D-Bus property of the SimpleInterface interface of the TpConnection object. So TpConnection should provide a way to get that information without requiring me to make a raw D-Bus call to org.freedesktop.DBus.Properties.Get().
*** This bug has been marked as a duplicate of bug 24107 ***
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