[clang] [lld] [llvm] [NFC] Cleanup in Support headers. (PR #104825)

[Nikita Popov via llvm-commits]

nikic wrote:

> For reference: [compile-time-tracker run](https://llvm-compile-time-tracker.com/compare.php?from=82fdfd4aa7f60b1f8e715211b925a7f2bfe57ea9&to=70b88a219999f2c8bc26a0178c6ae9aa2b0834e8&stat=instructions%3Au) with the change (please check the instructions:u for "clang build" at the bottom). See also [the per-file breakdown](https://llvm-compile-time-tracker.com/compare_clang.php?from=82fdfd4aa7f60b1f8e715211b925a7f2bfe57ea9&to=70b88a219999f2c8bc26a0178c6ae9aa2b0834e8&stat=instructions%3Au).

This shows compile-time regressions -- that really shouldn't happen for include changes.

https://github.com/llvm/llvm-project/pull/104825