Implement hasPrefix/hasSuffix in Swift

[frootloops]

But how can I test it?

I ran utils/build-script -RT but I'm not sure is that enough?

Testing Time: 1559.11s
  Expected Passes    : 7658
  Expected Failures  : 8
  Unsupported Tests  : 39
-- check-swift-all-macosx-x86_64 finished --
--- Finished tests for swift ---

[glessard]

#440

[gribozavr]

@frootloops It is sufficient testing, but you'd need to run that command on Linux. On OS X that code isn't even compiled.

[ogres]

Would not be better to compare characters one by one, without creating a range and a new substring ?