osmo-msc: free the VTY talloc context on exit

This is a follow up change before enabling the track of NULL talloc
contexts. Since there is no other way to deinitialize libosmovty,
let's free its root context on exit. Otherwise one would see
lots of memory chunks on exit...

Change-Id: I278f85f023210de6b4626d4493d10d20996f606a
1 file changed