[llvm] [LoopRotate] Remove canRotateDeoptimizingLatchExit and multi-rotate (PR #162482)

[Nikita Popov via llvm-commits]

nikic wrote:

> The canRotateDeoptimizingLatchExit check does not seem to work as intended. It was introduced in https://gitlab.azulsystems.com/dev/orca/-/commit/2f6987ba61cc31c16c64f511e5cbc76b52dc67b3 for the loop-rotate-multi-flag, where this flag was disabled and there was an intent to enable it by default later (https://reviews.llvm.org/D73058) and this has not happen even 5 years later.

Note that the first reference here is non-public, was that intentional?

https://github.com/llvm/llvm-project/pull/162482