[lldb] [llvm] DEBUGINFOD based DWP acquisition for LLDB (PR #70996)

[Michał Górny via llvm-commits]

mgorny wrote:

I've also confirmed that installing `LLVMDebuginfod` target won't help since it references other internal targets that are created at build-time and not included as part of the installed CMake configuration:

```
CMake Error at /usr/lib/llvm/18/lib64/cmake/llvm/LLVMExports.cmake:90 (set_target_properties):
  The link interface of target "LLVMDebuginfod" contains:

    httplib::httplib

  but the target was not found.  Possible reasons include:

    * There is a typo in the target name.
    * A find_package call is missing for an IMPORTED target.
    * An ALIAS target is missing.

Call Stack (most recent call first):
  /usr/lib/llvm/18/lib64/cmake/llvm/LLVMConfig.cmake:355 (include)
  cmake/modules/LLDBStandalone.cmake:9 (find_package)
  CMakeLists.txt:34 (include)
```

I suspect that even if we hadn't used the dylib at all and installed all static libraries, it would be impossible to build LLDB against this install of LLVM as it wouldn't know about `httplib::httplib` — that is, unless LLVM was built without httplib support.

https://github.com/llvm/llvm-project/pull/70996