[$] Accelerating the kernel's build process

Kernel developers do a lot of kernel builds. Since the kernel is not asmall program, those builds can take a fair amount of time, even on a fastmachine. The kernel also has a complex build system; it is probably fairto say that few developers truly understand it, and fewer still are willingto try to improve it. Lorenzo Stoakes, armed with LLM-based assistance,decided to give it a try, though, and has managed to reduce the time ittakes to build a kernel - and not by a small amount.