As the title states, drop support for libpcre.

The library has long reached EOL, which was announced even before the last version, 8.45, was released 3 years ago. The multitude of issues this library was constantly running into was the entire point for writing libpcre2, which released in 2015 (almost 10 years ago at this point) and is the replacement.[1]

libpcre is no longer maintained, and is steadily being flushed out of ports and package trees of most BSD and Linux distributions, while Zabbix thinks it should be the default pcre library in use, unless explicitly prohibited.

There are no modern day systems that don't have a version of PCRE2 available. If this causes user issues, they should probably upgrade their systems, but it shouldn't serve as rationale to keep obsolete code cruft around.

[1]: pcre.org