MINOR: stats: fix minor typo fix in stats_dump_errors_to_buffer()

Remove the space before the colon to match the format used in the frontend.
MINOR: Also accept SIGHUP/SIGTERM in systemd-wrapper

My proposal is to let haproxy-systemd-wrapper also accept normal
SIGHUP/SIGTERM signals to play nicely with other process managers
besides just systemd. In my use case, this will be for using with
runit which has to ability to change the signal used for a
"reload" or "stop" command. It also might be worth renaming this
bin to just haproxy-wrapper or something of that sort to separate
itself away from systemd. But that's a different discussion. :)
MEDIUM: http: enable header manipulation for 101 responses

Ryan Brock reported that server stickiness did not work for WebSocket
because the cookies and headers are not modified on 1xx responses. He
found that his browser correctly presents the cookies learned on 101
responses, which was not specifically defined in the WebSocket spec,
nor in the cookie spec. 101 is a very special case. Being part of 1xx,
it's an interim response. But within 1xx, it's special because it's
the last HTTP/1 response that transits on the wire, which is different
from 100 or 102 which may appear multiple times. So in that sense, we
can consider it as a final response regarding HTTP/1, and it makes
sense to allow header processing there. Note that we still ensure not
to mangle the Connection header, which is critical for HTTP upgrade to
continue to work smoothly with agents that are a bit picky about what
tokens are found there.

The rspadd rules are now processed for 101 responses as well, but the
cache-control checks are not performed (since no body is delivered).

Ryan confirmed that this patch works for him.

It would make sense to backport it to 1.5 given that it improves end
user experience on WebSocket servers.
BUG/MEDIUM: config: propagate frontend to backend process binding again.

This basically reverts 3507d5d ("MEDIUM: proxy: only adjust the backend's
bind-process when already set"). It was needed during the transition to
the new process binding method but is causing trouble now because frontend
to backend binding is not properly propagated.

This fix should be backported to 1.5.
MEDIUM: config: properly propagate process binding between proxies

We now recursively propagate the bind-process values between frontends
and backends instead of doing it during name resolving. This ensures
that we're able to properly propagate all the bind-process directives
even across "listen" instances, which are not perfectly covered at the
moment, depending on the declaration order.
MEDIUM: config: make the frontends automatically bind to the listeners' processes

When a frontend does not have any bind-process directive, make it
automatically bind to the union of all of its listeners' processes
instead of binding to all processes. That will make it possible to
have the expected behaviour without having to explicitly specify a
bind-process directive.

Note that if the listeners are not bound to a specific process, the
default is still to bind to all processes.

This change could be backported to 1.5 as it simplifies process
management, and was planned to be done during the 1.5 development phase.
MEDIUM: config: compute the exact bind-process before listener's maxaccept

This is a continuation of previous patch, the listener's maxaccept is divided
by the number of processes, so it's best if we can swap the two blocks so that
the number of processes is already known when computing the maxaccept value.
MEDIUM: config: only warn if stats are attached to multi-process bind directives

Some users want to have a stats frontend with one line per process, but while
100% valid and safe, the config parser emits a warning. Relax this check to
ensure that the warning is only emitted if at least one of the listeners is
bound to multiple processes, or if the directive is placed in a backend called
from multiple processes (since in this case we don't know if it's safe).
MEDIUM: config: report it when tcp-request rules are misplaced

A config where a tcp-request rule appears after an http-request rule
might seem valid but it is not. So let's report a warning about this
since this case is hard to detect by the naked eye.
DOC: indicate in the doc that track-sc* can wait if data are missing

Since commit 1b71eb5 ("BUG/MEDIUM: counters: fix track-sc* to wait on
unstable contents"), we don't need the "if HTTP" anymore. But the doc
was not updated to reflect this.

Since this change was backported to 1.5, this doc update should be
backported as well.
MINOR: config: detect the case where a tcp-request content rule has no inspect-delay

If a frontend has any tcp-request content rule relying on request contents
without any inspect delay, we now emit a warning as this will randomly match.

This can be backported to 1.5 as it reduces the support effort.