[clang] clang: __builtin_VARIABLE_NAME (PR #86756)

[Jon Roelofs via cfe-commits]

jroelofs wrote:

Here's an example of the awkward lengths Halide has to go through to do this without compiler support:

https://github.com/halide/Halide/blob/a132246ced07adc59c7b3631009464e5a14e0abb/src/Introspection.h#L19-L23

https://github.com/llvm/llvm-project/pull/86756