Fix ownership based deallocation pass crash (#179357) The `OwnershipBasedBufferDeallocation` pass crashes when the IR contains memrefs that are live in the same Block but are defined in different Blocks. During this pass, live memrefs in a given block are sorted according to the comparison function `ValueComparator`. This causes an assertion to be triggered when sorting memref values using `ValueComparator` as the comparison function. The assertion triggered is found in `Operation::isBeforeInBlock`, which requires `this` and `other` to reside in the same block. (See the definition [here](https://github.com/llvm/llvm-project/blob/main/mlir/lib/IR/Operation.cpp#L385-L386).) The fix is to handle values from different blocks in the `ValueComparator` by sorting based on Block number if the compared ops aren't in the same block. While `computeBlockNumber` is intended for debugging and error messages, it is a convenient utility that can provide a sufficient weak ordering for `llvm::sort` while handling operations from different parent blocks. I'm not aware of another ordering relation for Blocks that would be appropriate as well as cheap to compute here. I've added a test to exercise this that would fail otherwise. As I was already editing the test file, I thought I would refactor it according to the recommendations of the [MLIR Testing Guide](https://mlir.llvm.org/getting_started/TestingGuide/#contributor-guidelines) Fixes #137342 Fixes #116363
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