swift234

SILGen: Improve initialization implementation.
Prepare to do variable and return value initialization the smart way, by allocating the buffer first and then emitting the expression result directly into the buffer rather than by evaluating the expression then allocating and initializing the buffer. Create an Initialization class hierarchy that represents an uninitialized buffer or tuple of uninitialized buffers, and rewrite the argument and pattern binding logic to allocate and build up an Initialization first then emit the expression into it. The "emit into" part still needs to be implemented, as does tuple pattern binding ('var (a,b,c) = ...'). Disable some decls test that do tuple binding for now.

Swift SVN r3574