Unless a new toolchain update has been merged, users should not need to
rebuild their toolchain. Yet, the first thing they see in the build
documentation is to run `Meta/serenity.sh rebuild-toolchain`, which
might incorrectly lead them to use it whenever they encounter an error.
This is a waste of time and causes frustration.
Move any mentions of this option to `Troubleshooting.md` and add a note
to `BuildInstructions.md` about the toolchain build being a one-time
endeavor.
In distributions with newer versions of OpenSSL, when you run
Meta/serenity.sh rebuild-toolchain you'll get curl: (35)
error:0A000152:SSL routines::unsafe legacy renegotiation
disabled. This is because OpenSSL was compiled with legacy
renegotiation disabled by default. I've added instructions
to Documentation/BuildInstructions.md to solve this issue.
So far we've gotten away with using GCC 11 for Lagom and to compile the
toolchain, but via #15795 we discovered a compiler bug that has been
fixed in the latest version but would error the build with CI's GCC 11.
Time for an upgrade :^)
We already use ubuntu-22.04 images in most places, so this is pretty
straightforward. The only exception is Idan's self-hosted runner, which
uses Ubuntu Focal. LibJS should build fine with GCC 11, still.
This is no longer relevant for most users because due to an
unrelated change to Meta/run.sh the default display backend is now
SDL which does not exhibit this problem.
