Update the batch-mode-llvmIRHash-consistency test to use echo method for updating the timestamp

Author: shahmishal

test/multifile/batch-mode-llvmIRHash-consistency.swift

@@ -10,7 +10,8 @@
 
 // RUN: cp %t/main{,-old}.o
 // RUN: cp %t/other{,-old}.o
-// RUN: %{python} %S/../Inputs/make-old.py %t/*.swift
+// RUN: echo 'public enum E: Error {}' >%t/main.swift
+// RUN: echo >%t/other.swift
 
 // RUN: cd %t; %target-swift-frontend -c -g -enable-batch-mode -module-name main -primary-file ./main.swift -primary-file other.swift