[lit] Add missing import

Apparently llvm-lit.py does not execute this path

diff --git a/llvm/utils/lit/lit/run.py b/llvm/utils/lit/lit/run.py
index 15e8144..4d16399 100644 (file)
--- a/llvm/utils/lit/lit/run.py
+++ b/llvm/utils/lit/lit/run.py
@@ -1,5 +1,6 @@
 import multiprocessing
 import time
+import os
 
 import lit.Test
 import lit.util