This improves the load time of most brew commands. For an example of
one of the simplest commands this speeds up:
Without Bootsnap:
```
$ hyperfine 'git checkout master; brew help' 'git checkout optimise_requires; brew help'
Benchmark 1: git checkout master; brew help
Time (mean ± σ): 525.0 ms ± 35.8 ms [User: 229.9 ms, System: 113.1 ms]
Range (min … max): 465.3 ms … 576.6 ms 10 runs
Benchmark 2: git checkout optimise_requires; brew help
Time (mean ± σ): 383.3 ms ± 25.1 ms [User: 133.0 ms, System: 72.1 ms]
Range (min … max): 353.0 ms … 443.6 ms 10 runs
Summary
git checkout optimise_requires; brew help ran
1.37 ± 0.13 times faster than git checkout master; brew help
```
With Bootsnap:
```
$ hyperfine 'git checkout master; brew help' 'git checkout optimise_requires; brew help'
Benchmark 1: git checkout master; brew help
Time (mean ± σ): 386.0 ms ± 30.9 ms [User: 130.2 ms, System: 93.8 ms]
Range (min … max): 359.5 ms … 469.3 ms 10 runs
Benchmark 2: git checkout optimise_requires; brew help
Time (mean ± σ): 330.2 ms ± 32.4 ms [User: 93.4 ms, System: 73.0 ms]
Range (min … max): 302.9 ms … 413.9 ms 10 runs
Summary
git checkout optimise_requires; brew help ran
1.17 ± 0.15 times faster than git checkout master; brew help
```
This prevents `make` from trying to regenerate `info` files which may
have odd timestamps when this isn't set. See
Homebrew/homebrew-core#87470.
This actually also addresses a build failure we've seen in CI (see
Homebrew/homebrew-core#87641).
- remove usage on macOS as we don't care about it there
- don't error out on incompatibility but still store stdlib on Linux
- remove (now) unused methods
This probably has to wait until 2.7.0 now and will require a bunch of
formula changes/deprecations but we should probably start moving in this
direction given we're not installing any of these on our CI any more.
