r175580 - Allow llvm::Optional to work with types without default constructors.

[Jordan Rose]

This is awesome. I think you need to write a move constructor now too, though—otherwise you'll end up with two complete objects being destructed. (Consider Optional<std::string>.)

Also, at least in we've been trending towards lowercase method names for new methods (i.e. reset() instead of Reset()). Is that not the case in LLVM?

Jordan