* Use '/usr/bin/env bash', because not all distros put bash in /bin
(some in /usr/bin), and with NixOS it's even more complicated. This
should make it compatible across all distros.
* The 'set -euo pipefail' makes the script exit immediately on error,
otherwise it tries to continue e.g. running make when the CMake
configuration failed.
* Change to the directory the script sits in, in case it is ever called
from another directory.
* With CMake 4.x, declaring compatibility with version 3.5 straight up
errors. Passing the environment variable fixes this issue. See
https://gitlab.kitware.com/cmake/cmake/-/issues/26613 and
https://gitlab.kitware.com/cmake/cmake/-/issues/26698 for more info.
* CMake doesn't always emit Makefiles by default, so use `cmake --build'
to build using whatever method CMake will choose.
* Compile using all available cores, instead of only using a single CPU
core.
