- fixes#132303
- Moves dot2add from a language builtin to a target builtin.
- Sets the scaffolding for Sema checks for DX builtins
- Setup DirectX backend as able to have target builtins
- Adds a DX TargetBuiltins emitter in
`clang/lib/CodeGen/TargetBuiltins/DirectX.cpp`
This change adds a stub DirectX target for clang to enable targeting
dxil targets.
Reviewed By: pete
Differential Revision: https://reviews.llvm.org/D122085