Use 'as' bridging on Linux when using Swift 4.2

Introduced in swiftlang/swift-corelibs-foundation#1572

Author: jpsim

CHANGELOG.md

@@ -10,6 +10,9 @@
   use the `clean` action on `xcodebuild`.  
   [Norio Nomura](https://github.com/norio-nomura)
 
+* Use 'as' bridging on Linux when using Swift 4.2.  
+  [JP Simard](https://github.com/jpsim)
+
 ##### Bug Fixes
 
 * None.

Makefile

@@ -80,7 +80,10 @@ archive:
 release: package archive
 
 docker_test:
-	docker run -v `pwd`:`pwd` -w `pwd` --rm norionomura/swift:40 swift test
+	docker run -v `pwd`:`pwd` -w `pwd` --name sourcekitten --rm norionomura/swift:42 swift test --parallel
+
+docker_htop:
+	docker run -it --rm --pid=container:sourcekitten terencewestphal/htop || reset
 
 # http://irace.me/swift-profiling/
 display_compilation_time:

Source/SourceKittenFramework/LinuxCompatibility.swift

@@ -10,50 +10,50 @@ import Foundation
 
 extension Array {
     public func bridge() -> NSArray {
-#if os(Linux)
-        return NSArray(array: self)
-#else
+#if _runtime(_ObjC) || swift(>=4.1.50)
         return self as NSArray
+#else
+        return NSArray(array: self)
 #endif
     }
 }
 
 extension CharacterSet {
     public func bridge() -> NSCharacterSet {
-#if os(Linux)
-        return _bridgeToObjectiveC()
-#else
+#if _runtime(_ObjC) || swift(>=4.1.50)
         return self as NSCharacterSet
+#else
+        return _bridgeToObjectiveC()
 #endif
     }
 }
 
 extension Dictionary {
     public func bridge() -> NSDictionary {
-#if os(Linux)
-        return NSDictionary(dictionary: self)
-#else
+#if _runtime(_ObjC) || swift(>=4.1.50)
         return self as NSDictionary
+#else
+        return NSDictionary(dictionary: self)
 #endif
     }
 }
 
 extension NSString {
     public func bridge() -> String {
-#if os(Linux)
-        return _bridgeToSwift()
-#else
+#if _runtime(_ObjC) || swift(>=4.1.50)
         return self as String
+#else
+        return _bridgeToSwift()
 #endif
     }
 }
 
 extension String {
     public func bridge() -> NSString {
-#if os(Linux)
-        return NSString(string: self)
-#else
+#if _runtime(_ObjC) || swift(>=4.1.50)
         return self as NSString
+#else
+        return NSString(string: self)
 #endif
     }
 }