SR-3126: Decimal(Double.infinity) hangs forever
SR-3126: Decimal(Double.infinity) hangs forever

- Decimal doesnt fully support floating point so trap when initialised
  with Double.infinity.

- Also mark Decimal properties .infinity and .signalingNaN and
 formTruncatingRemainder(dividingBy:) as unavailable.

JGiola/swift-corelibs-foundation,alblue/swift-corelibs-foundation,apple/swift-corelibs-foundation,parkera/swift-corelibs-foundation,alblue/swift-corelibs-foundation,parkera/swift-corelibs-foundation,alblue/swift-corelibs-foundation,e78l/swift-corelibs-foundation,apple/swift-corelibs-foundation,alblue/swift-corelibs-foundation,e78l/swift-corelibs-foundation,apple/swift-corelibs-foundation,parkera/swift-corelibs-foundation,apple/swift-corelibs-foundation,e78l/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,alblue/swift-corelibs-foundation,apple/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,e78l/swift-corelibs-foundation,JGiola/swift-corelibs-foundation,parkera/swift-corelibs-foundation,e78l/swift-corelibs-foundation,parkera/swift-corelibs-foundation,JGiola/swift-corelibs-foundation