Auto merge of #47802 - bobtwinkles:loop_false_edge, r=nikomatsakis

[NLL] Add false edges out of infinite loops

Resolves #46036 by adding a `cleanup` member to the `FalseEdges` terminator kind. There's also a small doc fix to one of the other comments in `into.rs` which I can pull out in to another PR if desired =)

This PR should pass CI but the test suite has been relatively unstable on my system so I'm not 100% sure.

r? @nikomatsakis

diff --cc src/librustc/ich/impls_mir.rs
Simple merge

diff --cc src/librustc/mir/mod.rs
Simple merge

diff --cc src/librustc/mir/visit.rs
Simple merge

diff --cc src/librustc_mir/borrow_check/mod.rs
Simple merge

diff --cc src/librustc_mir/dataflow/impls/borrows.rs
Simple merge

diff --cc src/librustc_mir/transform/inline.rs
Simple merge

diff --cc src/librustc_mir/transform/qualify_consts.rs
Simple merge