Using `build_native_tool` directly doesn't seem to be standard, instead
other tools seem to call `setup_host_tool` (e.g. milr-linalg-ods-gen and
`add_tablegen` seems to have a copy of `setup_host_tool` internally).
When cross compiling llvm in two stages, the first building all native
tools and then the second using those built tools to cross compile, this
prevents the second stage from trying to rebuild mlir-irdl-to-cpp, which
fails.
f5006e0431