stack: add virtual destructor definition for class w/ virtual functions
stack: add virtual destructor definition for class w/ virtual functions

Signed-off-by: Kefu Chai <a4b264ee037c625052534d60505bfd0db4776ac4@redhat.com>
Message-Id: <f188c9ec2ce0c1338db441c6d4bcff5afcfa9875@gmail.com>

avikivity/seastar,syuu1228/seastar,syuu1228/seastar,cloudius-systems/seastar,dreamsxin/seastar,scylladb/seastar,scylladb/seastar,scylladb/seastar,dreamsxin/seastar,syuu1228/seastar,avikivity/seastar,cloudius-systems/seastar,cloudius-systems/seastar,avikivity/seastar,dreamsxin/seastar