The new git submodule src/llvm-project is a monorepo replacing src/llvm and src/tools/{clang,lld,lldb}. This also serves as a rebase for these projects to the new 8.x branch from trunk. The src/llvm-emscripten fork is unchanged for now.
Rename the previous enum debug info test, and add more tests to cover c-like enums and tagged (ordinary) enums.