switching back to a "Close" message-to-self without a response (as it had been
before dc3ff192 "Avoid further unwanted
interference of DbusIpcThread::execute/close").  Especially on a first start of
LO (where it restarts after creating the UserInstallation), it had been observed
that DbusIpcThread::close was blocked waiting on a reply in
dbus_connection_send_with_reply_and_block while DbusIpcThread::enable had
already successfully (i.e., without emitting any of the SAL_WARNs) proceeded
past sending the reply and was blocked on closeDone_.wait().  However that can
happen---it should be clear by now that I don't understand anything at all about
DBus.  :(

Change-Id: Id5f368a60b2d8dd8b7074308ac1ad6b6545131ff