Mark refresh-waiting transactions with REFRESH.

Mark refresh-waiting transactions with REFRESH.

Before this change, transactions initiating a refresh were still marked
as TCP_HIT*. If such a transaction was terminated (for any reason)
before receiving an IMS reply, it was logged with that misleading tag.
Now, such transactions are logged using TCP_REFRESH[_ABORTED].

After the refresh (successful or otherwise), the tag changes to one of
the other TCP_REFRESH_* values, as before.