New Attributes API

Hi LLVMers!

As many of you know, the Attributes APIs have changed dramatically. It has mostly solidified (there may be minor changes in the future). I've been asked to provide an upgrade path for people who use the Attributes APIs. I'll be working on one over the weekend and will get it out to you ASAP.

In the meantime, if you have any problems with the current APIs, please email me and I will help you as best as I can.