[php-src] PR #25257: Fix GH-25077: Send captured FPM worker output to syslog

Pull Request: https://github.com/php/php-src/pull/25257 Author: localzet FPM sends the master's stderr to /dev/null when error_log=syslog. With catch_workers_output=yes, worker output was always routed to that stderr instead of the existing syslog logger. Choose ZLOG_SYSLOG when the master is configured to use it; otherwise keep the stderr path. Add a Linux-only regression test that captures both worker stdout and stderr through a test-only LD_PRELOAD syslog interceptor, without needing a host syslog daemon. Skip if no compiler is available or PHP is 32-bit. The interceptor was compiled and smoke-tested with a glibc syslog caller, including _FORTIFY_SOURCE=2. Native PHP-FPM tests still need to be run.