tests: Check that backtrace() doesn't corrupt signal mask
tests: Check that backtrace() doesn't corrupt signal mask

Message-Id: <da73753b67f36e6919e0a6fa4942f3c2af211fe4@scylladb.com>

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