[clang] [clang] [Serialization] No transitive change for MacroID and PreprocessedEntityID (PR #166346)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> Also, can you please compile real-world modules (e.g. libc++) and show how this affects the PCM size?

In my simple test, it didn't affect the PCM size. It makes sense in the theory too. Since on the one hand, the number of MacroID and PreprocessedEntityID is much less than other IDs. And also, we didn't use VBR encoding for MacroID and PreprocessedEntityID in my memory. So it might not affect the PCM size significantly.

https://github.com/llvm/llvm-project/pull/166346