[clang] [clang][modules] Print library module manifest path. (PR #76451)

[Chuanqi Xu via cfe-commits]

ChuanqiXu9 wrote:

> > LGTM.
> > We need to delete `clang/test/Driver/Inputs/cxx23_modules/usr/lib/x86_64-linux-gnu/libc++.so` and `clang/test/Driver/Inputs/cxx23_modules/usr/lib/x86_64-linux-gnu/modules.json`, we should generate them with `split-file`
> 
> Are you sure that is the proper way? Should these tests not use a complete installation to make sure it works on installations?

We can use `mkdir` to generate more complex paths. For example,

```
// RUN: split-file %s %t
//
// RUN: mkdir %t/....
// RUN: touch %t/.../libc++.so
```


The intention is to remove the use of `Inputs` in test. It is really hard to read.

https://github.com/llvm/llvm-project/pull/76451