archivers/php-zstd: Update 0.15.2 => 0.16.0

Changelog:
https://github.com/kjdev/php-ext-zstd/releases/tag/0.16.0

Commit log:
https://github.com/kjdev/php-ext-zstd/compare/0.15.2...0.16.0

Patch config.m4 to always honor APCU setting.

PR: 295867
Sponsored by: UNIS Labs
Co-authored-by: Vladimir Druzenko <vvd@FreeBSD.org>