[GIT-PULLS] [php-src] PR #22704: GH-22617: avoid null byte truncation of persistent stream keys

Pull Request: https://github.com/php/php-src/pull/22704
Author: devnexen

Abstract unix domain socket addresses begin with a null byte, but the persistent stream list is keyed by a NUL-terminated string. The key was truncated at that null byte, so distinct abstract sockets collapsed onto the same persistent resource in p(f)sockopen() and stream_socket_client().

Escape null bytes (and backslashes, to stay unambiguous) when building the persistent hash key so the full address is preserved.