Adds XFRM state/policy flush when terminating which caused tests to fail
due to the check added with 9086f060d3 ("testing: Let test scenarios
fail if IPsec SAs or policies are not removed").
The tkm scenarios recently failed due to a segmentation fault on my host
because I had an old build of the tkm library already built in the build
directory. Because the stamp file was not versioned the new release was
never checked out or built and charon-tkm was linked against the old
version causing a segmentation fault during key derivation.
Tobias Brunner