swift234

Move sil-opt pass names and definitions into Passes.def.

This was the last bit of boilerplate associated with adding a new pass that had
not been added to Passes.def. Now to add a new pass, all you need to do is:

1. Add the pass to Passes.def.
2. Implement the pass in SILPasses and update the CMake files.

Swift SVN r29856