[clang] [llvm] [SPIR-V] Add builtin/intrinsic for subgroup ballot (PR #174862)

[Joseph Huber via cfe-commits]

jhuber6 wrote:

Updated, now hopefully no one tells me that someone added something for https://github.com/llvm/llvm-project/pull/174655 already too

https://github.com/llvm/llvm-project/pull/174862