[swift-3.0-branch] Introduce siphash for strings on non-ObjC platforms

[moiseev]

• Explanation: Use siphash for string hashing on non-ObjC platforms
• Scope of Issue: Introduces a more secure hashing algorithm
• Origination:
• Risk: Minimal
• Reviewed By: Dmitri Gribenko
• Testing: Ran the existing test suite.
• Directions for QA: N/A

Requires: swiftlang/swift-corelibs-foundation#634

rdar://problem/28289426

[moiseev]

@swift-ci Please test

[moiseev]

@swift-ci Please test

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - dbeb0f793f5d5e535b4f3a7c369d039099ef05b4
Test requested by - @moiseev

[swift-ci]

Build failed
Jenkins build - Swift Test OS X Platform
Git Commit - dbeb0f793f5d5e535b4f3a7c369d039099ef05b4
Test requested by - @moiseev

[tkremenek]

@swift-ci clean test linux

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - 4eecd78
Test requested by - @tkremenek

[tkremenek]

@moiseev this doesn't build on Linux.

[tkremenek]

swift-PR-Linux/branch-swift-3.0-branch/swiftpm/Sources/Basic/ByteString.swift:50:30: error: value of type 'String' has no member '_contiguousUTF8'
13:20:30         let stringPtrStart = string._contiguousUTF8
13:20:30                              ^~~~~~ ~~~~~~~~~~~~~~~
13:20:30 /home/buildnode/jenkins/workspace/swift-PR-Linux/branch-swift-3.0-branch/swiftpm/Sources/Basic/OutputByteStream.swift:176:30: error: value of type 'String' has no member '_contiguousUTF8'
13:20:30         let stringPtrStart = string._contiguousUTF8
13:20:30                              ^~~~~~ ~~~~~~~~~~~~~~~

[shahmishal]

Please test with:
swiftlang/swift-corelibs-foundation#634

@swift-ci Please test

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - 4eecd78
Test requested by - @shahmishal

[swift-ci]

Build failed
Jenkins build - Swift Test OS X Platform
Git Commit - 4eecd78
Test requested by - @shahmishal

[moiseev]

Please test with:
swiftlang/swift-package-manager#656

@swift-ci Please test

[swift-ci]

Build failed
Jenkins build - Swift Test Linux Platform
Git Commit - 4eecd78
Test requested by - @moiseev

[shahmishal]

Please test with:
swiftlang/swift-corelibs-foundation#634
swiftlang/swift-package-manager#656

@swift-ci Please test Linux

[tkremenek]

Swift 3.0.1 is meant to be a bug-fix release or take critical changes. This is a fairly significant semantic change to the behavior of hashing, that doesn't seem to fit either category. Let's take this for Swift 3.1.

[gribozavr]

@moiseev If you will be pulling these fixes into 3.1, please also take this commit: #4850

[lattner]

3.1 should rebranch from master.