swift234

Add temporary String benchmark

  C++:     ~231326 ns
 ObjC:     ~750604 ns
Swift: ~5827396474 ns == 25191x slower than C++!

The problems are all over the place. For example: while there are lots
of failures to inline generics, there is work in the runtime as well to
fix some cases where we call calloc() instead of use the swift cache.

Swift SVN r12225