bsc: handle RR Release messages

Receive RR Release messages if they happen during lchan release. Add RR Release
to the alt{}s in both f_expect_chan_rel() to cover a whole bunch of test cases,
and in f_tc_ho_out_fail_no_ho_detect() which has its own release expectations.

Before this, RR Release messages would typically be lost in the RSL.clear
recently removed by Ie1be30c3f109dda8c58c523df508211f8e20aad3.

However, I still expect tests to pass after this, since the current osmo-bsc
master has a bug that omits RR Release messages (since [1]).

By applying this patch, both the buggy osmo-bsc (omitting RR Release) and the
fix of that [2] should pass the BSC tests. So far by accepting whatever comes
along, and not complaining if it doesn't come along.

A subsequent patch will more precisely ensure that exactly the expected
messages will be sent by osmo-bsc (Ibc64058f1e214bea585f4e8dcb66f3df8ead3845).

[1] osmo-bsc I4fd582b41ba4599af704d670af83651d2450b1db
    commit 8b818a01b00ea3daad4ad58c162ac52b4f08a5cb
    "subscr conn: properly forget lchan before release"

[2] osmo-bsc I666b3b4f45706d898d664d380bd0fd2b018be358
    "fix: send RR Release (e.g. after BSSMAP Clear Cmd"

Related: OS#3413
Change-Id: I4e6d266d091b140f56b28312cb3c5d67ffcc3a59
1 file changed