Improve ClangCL compilation time on Windows.

[StefanStojanovic]

Version

main branch

Platform

Windows

Subsystem

build

What steps will reproduce the bug?

Compiling Node.js with ClangCL eg. running vcbuild.bat clang-cl.

How often does it reproduce? Is there a required condition?

Always.

What is the expected behavior? Why is that the expected behavior?

I expect small, subtle differences between MSVC and ClangCL compilation time.

What do you see instead?

ClangCL compilation is ~2.5 slower (less with x64, more with ARM64).

Additional information

The main difference is that ClangCL doesn't use precompiled headers, which MSVC does. There might be others too.

Refs: #52809

[StefanStojanovic]

Forgot to self-assign yesterday. I'm working on it and should have a PR for it this week.