[clang] [llvm] [DirectX] Add `--dx-embed-debug` and `--dx-pdb-path` flags (PR #204166)

[Ilia Kuklin via cfe-commits]

kuilpd wrote:

> Please revert this patch. The use of PdbDebugPath in DXILBitWriter/DXILWriterPass.cpp is a layering violation. It is defined in DXContainerGlobals.cpp, part of DirectXCodeGen, which depends on DXILBitWriter, not the other way round. This breaks enabling BUILD_SHARED_LIBS and, unlike typical breakages of that build that I've fixed over the years by adding missing dependencies to CMakeLists.txt (see [8763a68](https://github.com/llvm/llvm-project/commit/8763a68723b0dbd1ef2e7cc0ac61b2635ceef000), [acdb0c1](https://github.com/llvm/llvm-project/commit/acdb0c1f99a50ef357ac75ae1151991ca40aba10), [59b6c1b](https://github.com/llvm/llvm-project/commit/59b6c1b2d5290c40f59d2820b5144e2dec731635), [c92bf6b](https://github.com/llvm/llvm-project/commit/c92bf6b689a1b6c662f3fb30318c67257dbca864), [9f87bfe](https://github.com/llvm/llvm-project/commit/9f87bfe8bf2a3bd9b761e61c3cea3ccfec0553ec)), cannot be fixed that way.

If I define `PdbDebugPath` in DXILBitWriter/DXILWriterPass.cpp, and then use `extern PdbDebugPath` in DXContainerGlobals.cpp, will this fix the issue?

There is also `extern EmbedDebug` in DXILBitWriter/DXILWriterPass.cpp, which is defined in lib/MC/MCDXContainerWriter.cpp, is this dependency fine?

https://github.com/llvm/llvm-project/pull/204166