On MT call, there is a bug in CC conn use which leads to an early free and
use-after-free.
Add msc_vlr_test_call to show both MO and MT call legs separately and reproduce
the failure. It is visible in a sanitizer build (on debian 9).
A subsequent patch will fix the bug: If0659a878deb383ed0300217e2c41c8c79b2b6a5
Related: OS#2672
Change-Id: I6c3ca0c660388b1e2c82df17ec540c846201b0c7
Neels Hofmeyr