Walid Boudebouda

I brought back the comment mentioned by Dridi, hopefully this will make the diff a bit more readable. Otherwise, I don't see any way to break the commit into smaller...

- Changed the return value of `varnishadm -e` to `cli status / 100` after phk's suggestion during bugwash. That is because CLI status can go beyond 255 and we might...

Addressed dridi's comments: - Harmonized the exit status and documented them in EXIT STATUS section of the man page. - We don't forward the parsed heredoc now, we reconstruct it...

With this change, it seems that the default value for `thread_pool_stack` on 32 bit systems is no more sufficient (reason why `e00029.vtc` is failing on ubuntu_bionic).

Rebased and addressed all review comments. Ready for a (hopefully) last review.

I have addressed most of the last review items, and mentioned the potential drawbacks of this feature in the docs as requested during last bugwash.

PR updated: - [e8f35fb](https://github.com/varnishcache/varnish-cache/pull/4030/commits/e8f35fbf2af0c7bbf78c76e661136b0f75e9734c) changes wait_timeout to match with new timeout defaults. - [871f784](https://github.com/varnishcache/varnish-cache/pull/4030/commits/871f784f174f93f6777b5e7ba66d48be239f61e4) Notify client requests in the wait queue when the backend goes sick (as agreed during bugwash)

As per bugwash: squashed [e8f35fb](https://github.com/varnishcache/varnish-cache/pull/4030/commits/e8f35fbf2af0c7bbf78c76e661136b0f75e9734c) and removed [871f784](https://github.com/varnishcache/varnish-cache/pull/4030/commits/871f784f174f93f6777b5e7ba66d48be239f61e4) from this PR (to be submitted separately). Will merge once CCI is done.

I found something interesting about this: https://github.com/varnishcache/varnish-cache/commit/43af86cc40ed78a4b41be60fa3542e45ad644285

Thanks to @bsdphk 's [commit 22f5e216fb22ef4ae17b877ed80a99dc090123ed](https://github.com/varnishcache/varnish-cache/commit/22f5e216fb22ef4ae17b877ed80a99dc090123ed), all the tests are now passing successfully. Reviews are welcome.