No runtime includes

The title is a slight misnomer. This pull request does a few things that turned out to be coupled:

- Fix the windows build, which once again tracks trunk llvm

- Update nacl version to pepper_35 and track trunk pnacl llvm (fixes a bug in test_memoize on win32 under pnacl llvm)

- Avoid system includes (even the -ffreestanding ones - didn't work with pnacl on windows). Now uses compiler built-in macros for the stdint types, which should be more robust than the old old method.



Note, the README still says "Only glibc has been tried, not newlib", but AFAICT we actually only use newlib in our tests now (and glibc isn't recommended anymore).