Move intrinsics lowering pass from the optimization phase (where it
would not run if -Zmir-opt-level=0), to the drop lowering phase where it
runs unconditionally.

The implementation of those intrinsics in code generation and
interpreter is unnecessary. Remove it.

`crate.name` is already set by `tcx.crate_name`, there's no need to
override it.

…ulacrum

BTreeMap: more expressive local variables in merge

r? ```````@Mark-Simulacrum```````

…ulacrum

BTreeSet: simplify implementation of pop_first/pop_last

…and stop it interfering in rust-lang#79245.
r? ```````@Mark-Simulacrum```````

Optimization for bool's PartialOrd impl

Fix rust-lang#80034.

…Dylan-DPC

Always run intrinsics lowering pass

Move intrinsics lowering pass from the optimization phase (where it
would not run if -Zmir-opt-level=0), to the drop lowering phase where it
runs unconditionally.

The implementation of those intrinsics in code generation and
interpreter is unnecessary. Remove it.

Use more symbols in rustdoc

Builds on rust-lang#80044 and should not be merged before.

I want to test if this is actually faster before merging it, there was a lot of `to_string()` calls so I'm not sure it will actually help. That means I have to wait for 80044 to get merged before running perf.

r? `@ghost`