In LLVM unified builds `%swift_obj_root` points to `<LLVM build dir>/tools/swift`,
and folders like `bin`, `lib` and `share` are not under `swift_obj_root`, which
makes some tests fail.
For the cases in which `%swift_obj_root/lib` was used, replace it by
using `%swift-lib-dir` instead. Replicate `%swift-lib-dir` to create
`%swift-bin-dir` and `%swift-share-dir`, and use those instead of
`%swift_obj_root/bin` and `%swift_obj_root/share`.
This alternates work both in Swift build-script builds and also in LLVM
unified builds.
If a response file is being passed to the legacy driver
because it is too large to fit on the system's command line,
then it should also be passed when spawning the new driver.
Currently, however, the legacy driver attempts to pass the
*expanded* arguments to the new driver, which can cause the
invocation to fail, requiring the new driver to be disabled
in order to compile.
This change passes the original arguments into `run_driver`
as well as the expanded ones, so that the branch that spawns
the new driver can use the original arguments instead.
