[llvm] [SeperateConstOffsetFromGEP] Handle `or disjoint` flags (PR #76997)

[Nikita Popov via llvm-commits]

nikic wrote:

> As with other `or disjoint`-handling commits, this does not remove the existing check for the or's operands having no bits in common because `disjoint` is currently not inferred.

disjoint is inferred on the IR level, so you should remove the haveNoCommonBitsSet() call (and adjust tests that depend on it), unless there is some special circumstance here that requires otherwise.

https://github.com/llvm/llvm-project/pull/76997