[clang] Mechanically port bulk of x86 builtins to TableGen (PR #120831)

[Chandler Carruth via cfe-commits]

chandlerc wrote:

Ping, rebased to top-of-tree.

@phoebewang -- I think you're the most relevant reviewer here. If the `O` vs. `LL` thing is really a blocker despite the added information, I'd like to know so I can explore options to switch back. All of the ones I've come up with add complexity, so I'm hoping the current version is OK, but if its a blocker happy to start discussing what would work here.

I think the latest question was around MSVC / Windows where `long` in C and C++ is 32-bit, but AFAICT with my research in the standard, it is *always* 64-bits in OpenCL.

https://github.com/llvm/llvm-project/pull/120831