This is the C++ driver counterpart to a change that landed in the Swift
driver a while ago to use the clang-linker to determine what the default
linker is. This is to avoid hard-coding gold, which is deprecated and
not available on some newer Linux distributions. The challenge is that
these newer Linux distributions don't already have Swift so we have to
use the old C++ driver implementation.
When enabling the early swift driver on Windows, these tests need to be
adjusted for the new driver name that is reported. Add an additional
spelling for the driver to accommodate that for the testsuite.
This allows building the Swift standard library for targets which may
not have an actual OS running. This is identified by the OS field in
the target triple being set to `none`.
