swift

1520d7bc - [Sema] Remove 'deployment target ensures guard will always be true' (#3451)

[Sema] Remove 'deployment target ensures guard will always be true' (#3451) Remove the diagnostic that warns when an availability check is unnecessary because the minimum deployment target ensures it will always be true. This diagnostic is valuable (it tells users that they have dead fallback code) but can also be super annoying when a source file is shared between projects with different deployment targets. There is not currently a good mechanism to suppress these warnings (for example, by expressing a "compatibility version" in the source or as a build setting) and so it is better to turn the diagnostic off. rdar://problem/22337402 (cherry picked from commit c553de44787d41362495fcd045b718690b8ae7ad)