Bump llvm-project from 09f9db8 to c6a666f

Bumps [llvm-project](https://github.com/Xilinx/llvm-project) from `09f9db8` to `c6a666f`.
- [Commits](Xilinx/llvm-project@09f9db8...c6a666f)

---
updated-dependencies:
- dependency-name: llvm-project
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <[email protected]>