[clang] [clang-tools-extra] [clang] Trim large(-ish) includes from common headers (PR #216946)

[Alexis Engelke via cfe-commits]

https://github.com/aengelke requested changes to this pull request.

I wanted to get c-t-t numbers, but the build failed: https://llvm-compile-time-tracker.com/show_error.php?commit=76355f54b2bba62e530e658c88211eb80859a46e

Was the measurement with or without PCH?

https://github.com/llvm/llvm-project/pull/216946