[clang] Fix Lambda Mangling in Namespace-Scope Variable Initializers. (PR #159115)

[Zahira Ammarguellat via cfe-commits]

zahiraam wrote:

Thanks @tahonermann for finding the solution to the issue about the missing strings! Let me know if the changes in the tests are as expected. Meanwhile I will be working on creating more tests as Richard requested. 

https://github.com/llvm/llvm-project/pull/159115