[clang] [clang][Dependency Scanning] Move Module Timestamp Update After Compilation Finishes (PR #151774)

[Ben Langmuir via cfe-commits]

https://github.com/benlangmuir commented:

This change looks good to me, but can we add a test case? It seems like it ought to be possible to catch this in a lit test, even if it would only reproduce rarely.

https://github.com/llvm/llvm-project/pull/151774