tor-error, arti: Bump backtrace to 0.3.68.
Previously we were using backtrace 0.3.39, which has a bug that causes it to segault in some circumstances. I experienced this bug while trying to fix the minimal-versions build in !1508 (merged).
Previously we were using backtrace 0.3.39, which has a bug that causes it to segault in some circumstances. I experienced this bug while trying to fix the minimal-versions build in !1508 (merged).