[libclc] Use __scoped_atomic_udec/uinc_wrap to implement _clc_atomic_dec/inc#168327

wenju-he merged 3 commits intollvm:mainllvm/llvm-project:mainfrom

wenju-he:libclc-clc_atomic_inc.clwenju-he/llvm-project:libclc-clc_atomic_inc.clCopy head branch name to clipboard