Upgrade serf to 1.4 for openssl 1.1 support

[csandanov]

As was posted at #1856 (comment) currently pagespeed doesn't fully support openssl 1.1 because of apache serf dependency. Serf hasn't been issuing new releases in years but as was recommended by apache member in this maillist on a similar compilation issue topic it should be safe to use the code from branch 1.4

[oschaaf]

I did try that a little while ago, but backed off when I started to think that it's not a super straightforward change to make. There's also a WIP on another branch (called bazel) which has Envoy as a dependency. It is tempting to instead spend time to make the module switch to a fetcher based on Envoy's librarires instead, as that potentially brings in a whole lot of other perks, like h2/quic support, more stats, controllable connection pooling and regular releases to name a few.

[csandanov]

Any updates on this? I see envoy was merged into the master? Can we expect a release soon?

[oschaaf]

I anticipate that a release based on master is further away then one based on branch 36 (which tracks 1.14.x). The master branch needs work on the release process and then also on the Envoy port/fetching to get it in a shape where I’d be comfortable with releasing. Right now I’m the only one working on the bazel/absl/Envoy port (in spare time) and as such I cannot really commit to a schedule.