Rollup merge of #143785 - bjorn3:faster_ra_build_script_build, r=Kobzol

Add --compile-time-deps argument for x check

Together with skipping building C++ code in rustc_llvm for check, this reduces the amount of time it takes to do the x check for rust-analyzer analysis from 12m16s to 3m06s when the bootstrap compiler is already downloaded.

Author: matthiaskrgr