bpo-32713: Fix tarfile.itn for large/negative float values. (GH-5434)

bpo-32713: Fix tarfile.itn for large/negative float values. (GH-5434)

Import the tarfile changes from commit:

    commit 72d9b2be36f091793ae7ffc5ad751f040c6e6ad3
    Author: Joffrey F <f.joffrey@gmail.com>
    Date:   Mon Feb 26 16:02:21 2018 -0800

        bpo-32713: Fix tarfile.itn for large/negative float values. (GH-5434)

which add a safeguard against the type level volatility of
os.stat_result which will return a float instead of an int if e.
g. st_mtime becomes negative due to the timezone.