llvm-project

48a6df36 - Reapply "[Utils] Consolidate `LockstepReverseIterator` into own header (NFC)"

Reapply "[Utils] Consolidate `LockstepReverseIterator` into own header (NFC)" Common code has been unified and generalized. Original commit: 123dca9b56e1359d8ec7771ea3bd0afd4b1ea6af Previously reverted due to accidentally merged incompletely. The issue has been addressed by restoring missing code.