[Test][stdlib] Use /dev/stderr for lit compatibility

Author: ramonasuncion

test/stdlib/SwiftObjectNSObject.swift

@@ -16,7 +16,7 @@
 // RUN: %target-build-swift %s -g -I %S/Inputs/SwiftObjectNSObject/ -Xlinker %t/SwiftObjectNSObject.o -o %t/SwiftObjectNSObject
 // RUN: %target-codesign %t/SwiftObjectNSObject
 // RUN: %target-run %t/SwiftObjectNSObject 2> %t/log.txt
-// RUN: cat %t/log.txt 1>&2
+// RUN: cat %t/log.txt > /dev/stderr
 // RUN: %FileCheck %s < %t/log.txt
 // REQUIRES: executable_test