[llvm] [LTO] Hash consumed CGData in the ThinLTO cache key (PR #214161)

[Karim Alweheshy via llvm-commits]

karim-alweheshy wrote:

@kyulee @tejohnson, could one of you review this ThinLTO cache-key fix? It hashes consumed CGData bytes so replacing a file at a stable path cannot reuse objects generated from the previous contents. The reduced regression compares shared-cache output with a fresh-cache control, and the exact-head CI matrix is green.

https://github.com/llvm/llvm-project/pull/214161