[clang] [llvm] [clang][deps] Track directory dependencies of modules (PR #222202)

[Jan Svoboda via cfe-commits]

jansvoboda11 wrote:

Can you clarify what use-case does this capability serve?
> * letting the build system report which directories have been invalidated on
future incremental builds.

https://github.com/llvm/llvm-project/pull/222202