Auto merge of #88988 - Mark-Simulacrum:avoid-into-ok, r=nagisa

Auto merge of #88988 - Mark-Simulacrum:avoid-into-ok, r=nagisa

Avoid codegen for Result::into_ok in lang_start

This extra codegen seems to be the cause for the regressions in max-rss on #86034. While LLVM will certainly optimize the dead code away, avoiding it's generation in the first place seems good, particularly when it is so simple.

#86034 produced this [diff](https://gist.github.com/Mark-Simulacrum/95c7599883093af3b960c35ffadf4dab#file-86034-diff) for a simple `fn main() {}`. With this PR, that diff [becomes limited to just a few extra IR instructions](https://gist.github.com/Mark-Simulacrum/95c7599883093af3b960c35ffadf4dab#file-88988-from-pre-diff) -- no extra functions.

Note that these are pre-optimization; LLVM surely will eliminate this during optimization. However, that optimization can end up generating more work and bump memory usage, and this eliminates that.