[clang] [llvm] [Clang] Invoke pass plugin preCodeGenCallback (PR #171872)

[Grigor Nikolov via cfe-commits]

grigornik wrote:

Hi
On [clang-ppc64-aix](https://lab.llvm.org/buildbot/#/builders/64) test cases:
```
Clang::codegen-plugins.c (PR https://github.com/llvm/llvm-project/pull/171872)
Clang::pass-plugins.c (PR https://github.com/llvm/llvm-project/pull/173287)
```
fail on AIX https://lab.llvm.org/buildbot/#/builders/64/builds/6924
in similar way as `LLVM::codegen-plugin.ll`
https://lab.llvm.org/buildbot/#/builders/64/builds/6827/steps/6/logs/FAIL__LLVM__codegen-plugin_ll

With commit https://github.ibm.com/compiler/llvm-project/commit/f24c0ec4124e76e072200377a40c80f974cfb51f
you have xfailed `codegen-plugin.ll`
Can you please do same for 
```
Clang::codegen-plugins.c
Clang::pass-plugins.c
```
>From our side we will try to look at the original `codegen-plugin.ll` failure on AIX

https://github.com/llvm/llvm-project/pull/171872