Fix a bug in LogPacket.encode(inFormat:).

The source location should be encoded as (start line, start column, end line, end column), even though the function is (start line, end line, start column, end column).
This was caught by a soon-to-land port of the tests from the legacy PlaygroundLogger implementation to the new implementation.

Author: cwakamo

PlaygroundLogger/PlaygroundLogger/LogPacket+Encoding.swift

@@ -2,7 +2,7 @@
 //
 // This source file is part of the Swift.org open source project
 //
-// Copyright (c) 2017 Apple Inc. and the Swift project authors
+// Copyright (c) 2017-2018 Apple Inc. and the Swift project authors
 // Licensed under Apache License v2.0 with Runtime Library Exception
 //
 // See http://swift.org/LICENSE.txt for license information
@@ -21,8 +21,8 @@ extension LogPacket {
 
         // Encode the source location.
         encoder.encode(number: UInt64(startLine), allowShortEncoding: false)
-        encoder.encode(number: UInt64(endLine), allowShortEncoding: false)
         encoder.encode(number: UInt64(startColumn), allowShortEncoding: false)
+        encoder.encode(number: UInt64(endLine), allowShortEncoding: false)
         encoder.encode(number: UInt64(endColumn), allowShortEncoding: false)
 
         // Encode the thread ID.