swift234

stdlib: checkpoint 15612767: Int should become a separate, platform-sized type

1) Abstract away assumptions about all LLVM types being prefixed by 'Int'.
2) Thread through the ability to create a "word" sized type. This is
   blocked by a couple bugs.
3) Fix a bug where Int8/UInt8 did not conform to ArrayBounds.
   (This bug dates back to when FixedPoint.swift was hand maintained.)

Swift SVN r11858