swift234

Add a new tool called swift-llvm-opts that is a custom opt driver for swift.

Now that one can not use analysis groups anymore on LLVM, we were given two
choices. Reinsert that dynamicism so we could via opt -load add in analyses /or/
just create our own version of opt. I decided to go with the later since it
enables us to simulate how IRGen sets up the LLVM pass pipeline exactly,
something we were unable to do before.

This also sets us up for whenever we need to respond to the new pass manager.

Swift SVN r32808