[clang-tools-extra] [clangd] Support .clangd command line modifications for C++ modules (PR #122606)

[Chuanqi Xu via cfe-commits]

https://github.com/ChuanqiXu9 commented:

Do we need to update `buildModuleFile` in `clang-tools-extra/clangd/ModulesBuilder.cpp` to update the commands to build the module interfaces?

https://github.com/llvm/llvm-project/pull/122606