[Foundation] CocoaError.Code, URLError.Code: Remove hashValue implementation

These implementations did not produce the same hash values as the raw value. RawRepresentable provides a correct hashing implementation by default, so let’s just use that.

Author: lorentey

stdlib/public/Darwin/Foundation/NSError.swift

@@ -570,10 +570,6 @@ public struct CocoaError : _BridgedStoredNSError {
     public init(rawValue: Int) {
       self.rawValue = rawValue
     }
-    
-    public var hashValue: Int {
-      return self.rawValue
-    }
   }
 }
 
@@ -1801,10 +1797,6 @@ public struct URLError : _BridgedStoredNSError {
     public init(rawValue: Int) {
       self.rawValue = rawValue
     }
-
-    public var hashValue: Int {
-      return self.rawValue
-    }
   }
 }