Fix `broken-pipe-no-ice` run-make test for rpath-less builds
The `broken-pipe-no-ice` run-make test currently fails on rpath-less builds, because host compiler runtime libs are not configured for raw std command usages.
This PR is an alternative approach to #140744. However, instead of duplicating `run_make_support::util::set_host_compiler_dylib_path` logic, we instead support "ejecting" the "configured" underlying std `Command` from `bare_rustc()` and `rustdoc()`, where host compiler runtime libs are already set.
cc `@jchecahi`
r? `@Kobzol`
The run-make test suite contains tests which are the most flexible out of all the rust-lang/rust test suites. run-make tests can basically contain arbitrary code, and are supported by the run_make_support library.
Infrastructure
A run-make test is a test recipe source file rmake.rs accompanied by its parent directory (e.g. tests/run-make/foo/rmake.rs is the foorun-make test).
The setup for the rmake.rs can be summarized as a 3-stage process:
First, we build the run_make_support library in bootstrap as a tool lib.
Then, we compile the rmake.rs "recipe" linking the support library and its dependencies in, and provide a bunch of env vars. We setup a directory structure within build/<target>/test/run-make/
<test-name>/
rmake.exe # recipe binary
rmake_out/ # sources from test sources copied over
and copy non-rmake.rs input support files over to rmake_out/. The support library is made available as an extern prelude.
Finally, we run the recipe binary and set rmake_out/ as the working directory.
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