[llvm] Reapply "RuntimeLibcalls: Use get_host_tool_path for executables used … (#159488) (PR #159489)

[Alex Bradbury via llvm-commits]

asb wrote:

I won't be able to look into this more until tomorrow, but this seems to have broken the RISC-V cross-build bots e.g. https://lab.llvm.org/buildbot/#/builders/87/builds/3257

https://github.com/llvm/llvm-project/pull/159489