- Forward several environment variables to the test environment because
Windows uses them to inform the processes about things like the number
of processors and the architecture.
- Normalize some literal Unix paths to be the same as the results in
Windows, that will have forward slashes and the drive letter.
- Skip some test that use build-script-impl and tests that check for
files being executable (everything is executable in Windows).
- Don't use the owner and group arguments for tar on Windows.
- Hide the stderr output of which. In Windows it prints the full PATH in
case of failures, which is disrupting.
- Quote many paths in Windows in the output of build-script results.
- Provide a version of mock-distcc that can be executed in Windows. The
raw Python script cannot.
- Change the expected results for clang/clang++ to the right values in
Windows (clang-cl in both cases).
Why are the python reasons for having our code nested in a directory
called ``swift_build_support.swift_build_support/`` instead of simply
``swift_build_support/``? Is that what we really want here?
