Add --vg-arg option to clang test runner.
 - Passes additional argument through to valgrind.

Also, don't run valgrind with --leak-check=no by default.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@80981 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/utils/test/TestingConfig.py b/utils/test/TestingConfig.py
index a43bd76..b611d78 100644
--- a/utils/test/TestingConfig.py
+++ b/utils/test/TestingConfig.py
@@ -20,6 +20,7 @@
         self.root = None
         self.useValgrind = None
         self.useExternalShell = None
+        self.valgrindArgs = []
 
         # FIXME: These need to move into a substitutions mechanism.
         self.clang = None