[3.14] gh-143637: Fix re-entrant mutation of ancillary data in socket.sendmsg() ...

[3.14] gh-143637: Fix re-entrant mutation of ancillary data in socket.sendmsg() (GH-143892) (#144786)

gh-143637: Fix re-entrant mutation of ancillary data in socket.sendmsg() (GH-143892)
(cherry picked from commit 82b92e3cd180723a354cdeb0f0f1d593f1b5eb0d)

Co-authored-by: Priyanshu Singh <priyanshu2282@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Victor Stinner <vstinner@python.org>
Co-authored-by: Bénédikt Tran <10796600+picnixz@users.noreply.github.com>