Switch to upstream 2.39 release
    
    Upstream commit: ef321e23c20eebc6d6fb4044425c00e6df27b05f
    
    - Document CVE-2023-6246, CVE-2023-6779, and CVE-2023-6780
    - Update advisory format and introduce some automation
    - manual/io: Fix swapped reading and writing phrase.
    - Fix typo
    - S390: Fix building with --disable-mutli-arch [BZ #31196]
    - NEWS: insert advisories and fixed bugs for 2.39
    - contrib.texi: update
    - INSTALL, install.texi: minor updates, regenerate
    - libc.pot: regenerate
    - version.h, include/features.h: Bump version to 2.39
    - Create ChangeLog.old/ChangeLog.28