swift234

Make most of the standard library types Hashable.

This makes the integral, floating-point, character, bool, range,
string-byte, unsafe pointer, word, and NSObject types
Hashable. Specific notes:
  - Floating-point values use awful truncation-to-integer hashing due
  to <rdar://problem/14193818>
  - Classes don't have a default hash operation, although presumably
  they could.
  - hash() has been renamed to hashValue() to avoid conflicting with
    -[NSObject hash]. It's not a property due to
    <rdar://problem/14195801>.



Swift SVN r5658