Add `Float16`

Dante-Broggi · December 13, 2019, 5:01pm

Do note that that type alias has this comment on top of it:

apple/swift/blob/d3da328b8a8d4d5cceff39b5bb29b5c35efec446/stdlib/public/core/Policy.swift#L66-L75


      
          //===----------------------------------------------------------------------===//
          // Aliases for floating point types
          //===----------------------------------------------------------------------===//
          // FIXME: it should be the other way round, Float = Float32, Double = Float64,
          // but the type checker loses sugar currently, and ends up displaying 'FloatXX'
          // in diagnostics.
          /// A 32-bit floating point type.
          public typealias Float32 = Float
          /// A 64-bit floating point type.
          public typealias Float64 = Double