This shunts all the complexity of siphoning off the drop-use facts
into `LivenessResults::add_extra_drop_facts()`, which may or may
not be a good approach.

When a lazy logical operator (`&&` or `||`) occurs outside of an `if`
condition, it normally doesn't have any associated control-flow branch, so we
don't have an existing way to track whether it was true or false.

This patch adds special code to handle this case, by inserting extra MIR blocks
in a diamond shape after evaluating the RHS. This gives us a place to insert
the appropriate marker statements, which can then be given their own counters.

We do this for `&*` and `&mut*` already; might as well do it for raw pointers too.

…g, r=oli-obk

Revert propagation of drop-live information from Polonius

rust-lang#64749 introduced a flow of drop-use data from Polonius to `LivenessResults::add_extra_drop_facts()`, which makes `LivenessResults` agree with Polonius on liveness in the presence of free regions that may be dropped. Later changes accidentally removed this flow. This PR restores it.

…-obk

Apply `x clippy --fix` and `x fmt` on Rustc

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Just run `x clippy --fix` and `x fmt`, and remove some changes like `impl Default`.

coverage: Optionally instrument the RHS of lazy logical operators

(This is an updated version of rust-lang#124644 and rust-lang#124402. Fixes rust-lang#124120.)

When `||` or `&&` is used outside of a branching context (such as the condition of an `if`), the rightmost value does not directly influence any branching decision, so branch coverage instrumentation does not treat it as its own true-or-false branch.

That is a correct and useful interpretation of “branch coverage”, but might be undesirable in some contexts, as described at rust-lang#124120. This PR therefore adds a new coverage level `-Zcoverage-options=condition` that behaves like branch coverage, but also adds additional branch instrumentation to the right-hand-side of lazy boolean operators.

---

As discussed at rust-lang#124120 (comment), this is mainly intended as an intermediate step towards fully-featured MC/DC instrumentation. It's likely that we'll eventually want to remove this coverage level (rather than stabilize it), either because it has been incorporated into MC/DC instrumentation, or because it's getting in the way of future MC/DC work. The main appeal of landing it now is so that work on tracking conditions can proceed concurrently with other MC/DC-related work.

`@rustbot` label +A-code-coverage

…-obk

Also InstSimplify `&raw*`

We do this for `&*` and `&mut*` already; might as well do it for raw pointers too.

r? mir-opt