Log Message:
www/passenger: Update to 5.2.3.

- Fuse Panel support: fixes a few bugs with handling small log files
  and with apps that don't output any messages.
- Python app support: fixes a Python 3 compatibility issue w.r.t.
  writing data over the socket.
- macOS support: fixes a crash in the `passenger-config
  compile-nginx-engine` command which only occurs on macOS >= 10.13.
- Fixes a small memory corruption issue (dangling pointer) in the
  ApplicationPool subsystem.
- Improves support for the $TMPDIR environment variable by removing
  leftover hardcoded references to /tmp. Closes GH-2052.
- Updated PCRE version to 8.42 (was: 8.41) across the board.