[libclc] [libclc] Restore always_inline for SPIR-V targets (PR #202891)

[via cfe-commits]

Eric-Guo-NXP wrote:

> This sounds like a toolchain problem if you compile at `-O0` and want inlining for correctness.

O0 flag is from AddLibclc.cmake

https://github.com/llvm/llvm-project/pull/202891