[llvm] [Runtimes] Merge 'compile_commands.json' files from runtimes build (PR #116303)

[Shilei Tian via llvm-commits]

shiltian wrote:

That is fine. We don't want to change the semantics of top level configure, and also don't want to have any stale commands in it if only the top level configure runs.

https://github.com/llvm/llvm-project/pull/116303