[clang] [clang] Implement __builtin_stdc_rotate_left, __builtin_stdc_rotate_right (PR #160259)

[Erich Keane via cfe-commits]

https://github.com/erichkeane commented:

1 question in docs, else this is going to be fine for me.

https://github.com/llvm/llvm-project/pull/160259