[clang] [serialization] no transitive decl change (PR #92083)

[Michael Buch via cfe-commits]

Michael137 wrote:

Unfortunately this is still failing one test on the macOS CI: https://green.lab.llvm.org/job/llvm.org/view/LLDB/job/as-lldb-cmake/5083/execution/node/97/log

```
======================================================================
FAIL: test_duplicate_decls_gmodules (TestTemplateWithSameArg.TestTemplateWithSameArg)
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/packages/Python/lldbsuite/test/lldbtest.py", line 1756, in test_method
    return attrvalue(self)
  File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/test/API/lang/cpp/gmodules/template-with-same-arg/TestTemplateWithSameArg.py", line 66, in test_duplicate_decls
    self.filecheck("target module dump ast", __file__)
  File "/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/packages/Python/lldbsuite/test/lldbtest.py", line 2293, in filecheck
    self.assertTrue(cmd_status == 0)
AssertionError: False is not true
Config=arm64-/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/lldb-build/bin/clang
----------------------------------------------------------------------
Ran 2 tests in 1.682s

FAILED (failures=1)
```

Let me know if you need help reproducing this.

Looks like we're doing a FileCheck on the imported LLDB AST:
```
FileCheck output:

/Users/ec2-user/jenkins/workspace/llvm.org/as-lldb-cmake/llvm-project/lldb/test/API/lang/cpp/gmodules/template-with-same-arg/TestTemplateWithSameArg.py:69:10: error: CHECK: expected string not found in input
# CHECK: ClassTemplateSpecializationDecl {{.*}} imported in Module2 struct ClassInMod3 definition
```

But instead of `imported in Module2 struct ClassInMod3 definition` it's now just `imported struct ClassInMod3 definition`

https://github.com/llvm/llvm-project/pull/92083