PCRE library - to maintainer version

[leyao-daily]

There are two major versions of the PCRE library. The current version, PCRE2, released in 2015, is now at version 10.39.

The older, but still widely deployed PCRE library, originally released in 1997, is at version 8.45. This version of PCRE is now at end of life, and is no longer being actively maintained. Version 8.45 is expected to be the final release of the older PCRE library, and new projects should use PCRE2 instead.

I think it can be easily compiled to wasm library based on https://github.com/leyao-daily/pcre2 and we may modify ModSecurity configuration to accept this update.

[M4tteoP]

Based on this comment, PCRE is still a needed dependency even if we enable PCRE2. So, to make it work, I think we have to build pcre2 and provide it to modsec with a proper configuration on top of what we already have. I would suggest doing tries on top of #24, just because of the updated emsdk (if we feel that that PR is going to be okay).

[jcchavezs]

Relevant:

• PCRE2 support still requires PCRE1 owasp-modsecurity/ModSecurity#2750
• Add PCRE2 support to ModSecurity v2 owasp-modsecurity/ModSecurity#2737
• Add support for PCRE2 owasp-modsecurity/ModSecurity#2668