Improve OS check

Author: ikesyo

Sources/Nimble/Matchers/BeginWith.swift

@@ -17,12 +17,12 @@ public func beginWith(_ startingElement: Any) -> Predicate<NMBOrderedCollection>
     return Predicate.simple("begin with <\(startingElement)>") { actualExpression in
         guard let collection = try actualExpression.evaluate() else { return .fail }
         guard collection.count > 0 else { return .doesNotMatch }
-        #if os(Linux)
+        #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
+            let collectionValue = collection.object(at: 0) as AnyObject
+        #else
             guard let collectionValue = collection.object(at: 0) as? NSObject else {
                 return .fail
             }
-        #else
-            let collectionValue = collection.object(at: 0) as AnyObject
         #endif
         return PredicateStatus(bool: collectionValue.isEqual(startingElement))
     }

Sources/Nimble/Matchers/EndWith.swift

@@ -25,12 +25,12 @@ public func endWith(_ endingElement: Any) -> Predicate<NMBOrderedCollection> {
         guard let collection = try actualExpression.evaluate() else { return .fail }
 
         guard collection.count > 0 else { return PredicateStatus(bool: false) }
-        #if os(Linux)
+        #if os(macOS) || os(iOS) || os(tvOS) || os(watchOS)
+            let collectionValue = collection.object(at: collection.count - 1) as AnyObject
+        #else
             guard let collectionValue = collection.object(at: collection.count - 1) as? NSObject else {
                 return .fail
             }
-        #else
-            let collectionValue = collection.object(at: collection.count - 1) as AnyObject
         #endif
 
         return PredicateStatus(bool: collectionValue.isEqual(endingElement))