[3.12] gh-126775: make linecache.checkcache threadsafe and GC re-entrency safe (GH-126776) (#127779)

gh-126775: make linecache.checkcache threadsafe and GC re-entrency safe (GH-126776)

(cherry picked from commit 2233c303e476496fc4c85a29a1429a7e4b1f707b)

Co-authored-by: Thomas Grainger <tagrain@gmail.com>
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Bartosz Sławecki <bartoszpiotrslawecki@gmail.com>