devel/libqb: update 2.0.6 → 2.0.8, fix CVE-2023-39976, take maintainership

log_blackbox.c in libqb before 2.0.8 allows a buffer overflow via long
log messages because the header size is not considered.
https://nvd.nist.gov/vuln/detail/CVE-2023-39976

Changelogs:
https://github.com/ClusterLabs/libqb/releases/tag/v2.0.7
https://github.com/ClusterLabs/libqb/releases/tag/v2.0.8

Improve port: remove GNU_CONFIGURE_MANPREFIX, update pkg-descr, fix
warnings from portclippy.

PR: 282536
MFH: 2024Q4
(cherry picked from commit c08f528cd36c76d76f221e7af8d5918054978bdf)