HAproxy-1.8.8

[RELEASE] Released version 1.8.8

Released version 1.8.8 with the following main changes :
- BUG/MEDIUM: threads: Fix the max/min calculation because of name clashes
- BUG/MEDIUM: connection: Make sure we have a mux before calling detach().
- BUG/MINOR: http: Return an error in proxy mode when url2sa fails
- BUG/MEDIUM: kqueue: When adding new events, provide an output to get errors.
- BUG/MINOR: cli: Guard against NULL messages when using CLI_ST_PRINT_FREE
- MINOR: cli: Ensure the CLI always outputs an error when it should
- DOC: lua: update the links to the config and Lua API
- BUG/CRITICAL: h2: fix incorrect frame length check