Add helper for case-independent string equality checks

(cherry picked from commit bd47b0dac4a1ff6e686c99b9958693e86d44007b)

Gbp-Pq: Name Add-helper-for-case-independent-string-equality-checks.patch

systemd (247.3-7+deb11u6) bullseye-security; urgency=medium

  * Non-maintainer upload by the LTS Team.
  * CVE-2023-7008: Don't accept records of DNSSEC-signed domains
    when they have no signature.
  * CVE-2023-50387: DNSSEC denial of service (CPU consumption)
  * CVE-2023-50868: DNSSEC denial of service (CPU consumption)

[dgit import unpatched systemd 247.3-7+deb11u6]

Import systemd_247.3-7+deb11u6.debian.tar.xz

[dgit import tarball systemd 247.3-7+deb11u6 systemd_247.3-7+deb11u6.debian.tar.xz]

Import systemd_247.3.orig.tar.gz

[dgit import orig systemd_247.3.orig.tar.gz]