[tests] Add one more lit rename update I missed.

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@188117 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/lit.common.unit.cfg b/lib/lit.common.unit.cfg
index ca00abb..ccc3ffa 100644
--- a/lib/lit.common.unit.cfg
+++ b/lib/lit.common.unit.cfg
@@ -6,6 +6,8 @@
 
 import os
 
+import lit.formats
+
 # Setup test format
 llvm_build_mode = getattr(config, "llvm_build_mode", "Debug")
 config.test_format = lit.formats.GoogleTest(llvm_build_mode, "Test")