* "Reland Clang 11, roll buildroot to 1bc40a5f916adb93d87e2a2230a0ec43db876c1c, take 4 (#17467)" (#17482)"

This reverts commit 8166a91b.

* format code

* Roll buildroot to 3a27de1c5bb0f50be7d3efe3e00de4f6068c9f30