[clang] [clang][deps] Skip slow `UNHASHED_CONTROL_BLOCK` records (PR #69975)

[Jan Svoboda via cfe-commits]

jansvoboda11 wrote:

> Besides deps scanning, have you tried to enable these option to compile with clang modules? I mean, if it is safe to enable such options at compilation times, it looks a valid optimization for C++20 modules too.

I did not. I suspect it won't show in profiles of compiles the same way it does for scans, where this kind of overhead gets exacerbated.

> If it is not safe to do so, I think we need to document it explicitly.

This is a `-cc1`-only flag, so I don't think documenting the nuances/implications is super important.

https://github.com/llvm/llvm-project/pull/69975