Move a flaky process test out of libstd

This test ensures that everything in `env::vars()` is inherited but
that's not actually true because other tests may add env vars after we
spawn the process, causing the test to be flaky! This commit moves the
test to a run-pass test where it can execute in isolation.

Along the way this removes a lot of the platform specificity of the
test, using iteslf to print the environment instead of a foreign process.

0 files changed, 0 insertions, 0 deletions