[clang] [clang] Fix crash 'Cannot get layout of forward declarations' during CTU static analysis (PR #156056)

[Balázs Kéri via cfe-commits]

balazske wrote:

I still see a buildbot error in the clang-ppc64-aix builder:
```
sed -i='' 's/$/.ast/' /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/tools/clang/test/Analysis/Output/ctu-import-type-decl-definition.c.tmp/externalDefMap.txt # RUN: at line 8
+ sed -i= 's/$/.ast/' /home/llvm/llvm-external-buildbots/workers/aix-ppc64/clang-ppc64-aix/build/tools/clang/test/Analysis/Output/ctu-import-type-decl-definition.c.tmp/externalDefMap.txt
sed: illegal option -- i
Usage:  sed [-n] [-u] Script [File ...]
        sed [-n] [-u] [-e Script] ... [-f Script_file] ... [File ...]
```
Probably we need to find another way to get the **externalDefMap.txt**.

https://github.com/llvm/llvm-project/pull/156056