Add notes for SCA.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58373 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/NOTES.TXT b/lib/Analysis/NOTES.TXT
index c20c9f0..97b7bf7 100644
--- a/lib/Analysis/NOTES.TXT
+++ b/lib/Analysis/NOTES.TXT
@@ -18,3 +18,7 @@
 Investigate what classes of exprs are passed silently in GRExprEngine::Visit().
 
 One is PredefinedExpr.
+
+//===----------------------------------------------------------------------===//
+
+Remove PersistentSValPairs and PersistentSVals?