Remove old Windows Code

Windows now has a database (the registry) and can handle GMT/UTC, so
this is irrelevant code.

Author: gmittert

Foundation/NSTimeZone.swift

@@ -29,16 +29,6 @@ open class NSTimeZone : NSObject, NSCopying, NSSecureCoding, NSCoding {
     }
 
     public init?(name tzName: String, data aData: Data?) {
-#if os(Windows)
-        var tzName = tzName
-        if tzName == "UTC" || tzName == "GMT" {
-            tzName = "GMT+0000"
-        }
-        else if !(tzName.hasPrefix("GMT+") || tzName.hasPrefix("GMT-")) {
-            NSLog("Time zone database not available on Windows")
-        }
-#endif
-        
         super.init()
 
         /* From https://developer.apple.com/documentation/foundation/nstimezone/1387250-init: