lit: Normalize pathsep slashes also on %T.

On Python-w32 with mingw msys bash, %T was replaced to "x:\foo\bar...". msys bash cannot handle DOSish paths.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@138852 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/lit/lit/TestRunner.py b/utils/lit/lit/TestRunner.py
index 0cc1f394..f5f7c19 100644
--- a/utils/lit/lit/TestRunner.py
+++ b/utils/lit/lit/TestRunner.py
@@ -406,6 +406,7 @@
     if normalize_slashes:
         sourcepath = sourcepath.replace('\\', '/')
         sourcedir = sourcedir.replace('\\', '/')
+        tmpDir = tmpDir.replace('\\', '/')
         tmpBase = tmpBase.replace('\\', '/')
 
     # We use #_MARKER_# to hide %% while we do the other substitutions.