See https://github.com/docker-library/php/pull/1028#issuecomment-649763859 for details -- Someone™ needs to dig into the `pdo_mysql` build issue for this to return:
> `PHP Warning: PHP Startup: Unable to load dynamic library 'pdo_mysql.so' (tried: /usr/local/lib/php/extensions/no-debug-zts-20190128/pdo_mysql.so (Error relocating /usr/local/lib/php/extensions/no-debug-zts-20190128/pdo_mysql.so: _tsrm_ls_cache: initial-exec TLS resolves to dynamic definition in /usr/local/lib/php/extensions/no-debug-zts-20190128/pdo_mysql.so)`
