This changes the install layout to be similar across Darwin and
non-Darwin platforms. This will enable simplifying the user experience,
build infrastructure, and the driver as the SDK layout converges towards
a single layout on all the platforms.
This is the Linux equivalent of 3731a2ff0. There's probably a way to
merge them into one file cleanly, but the extra linker args on OS X
make it a little tricky. I'm deciding not to worry about it right now.