[clang] [Clang][OpenCL] Fix Missing `-fdeclare-opencl-builtins` When Using `--save-temps` (PR #131017)

[Shilei Tian via cfe-commits]

shiltian wrote:

Yeah these are implemented in bitcode file, therefore it needs the front end to be able to recognize it instead of treating it as an unknown symbol.

https://github.com/llvm/llvm-project/pull/131017