[Commit] Block specification work ahead

I have recently begun the process of

  1. revising the Blocks ABI spec to reflect recent changes; this is now complete.
  2. revising the Blocks Language spec in preparation for the upcoming C Standards Meeting
  3. updating the repository to reflect latest Apple internal practice (zero bug fixes AFAIK, but formatting and debugging info)

I will be doing this pretty much in the open while I churn through what I need to do and will not in particular seek review of the spec changes. There have been long dormant spec bug fixes suggested, I will do my best to fold all comments received to this point into the specifications.

As part of this I expect to produce a more “normal” LLVM docs document, e.g. take it out of .txt format.

Conceptually, though, I just renamed the Apple Blocks ABI spec from the name BlockImplementation.txt to Block-ABI-Apple.txt as a notice that, in general, a platform has its own choices of internal ABI, and that there is as yet no interest in keeping a single document as a source for all ABIs.

I will also be the first to admit that both specifications, language and ABI, need a lot of work, and I welcome input as to what and how to cover in these specifications!

Blaine Garst