[analyzer] When a symbol is null, we should track its constraints.

Because of this, we would previously emit NO path notes when a parameter
is constrained to null (because there are no stores). Now we show where we
made the assumption, which is much more useful.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@161280 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
index a002254..a94d7a7 100644
--- a/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
+++ b/lib/StaticAnalyzer/Checkers/DereferenceChecker.cpp
@@ -166,10 +166,8 @@
                   buf.empty() ? BT_null->getDescription() : buf.str(),
                   N);
 
-  report->addVisitor(
-    bugreporter::getTrackNullOrUndefValueVisitor(N,
-                                                 bugreporter::GetDerefExpr(N),
-                                                 report));
+  bugreporter::addTrackNullOrUndefValueVisitor(N, bugreporter::GetDerefExpr(N),
+                                               report);
 
   for (SmallVectorImpl<SourceRange>::iterator
        I = Ranges.begin(), E = Ranges.end(); I!=E; ++I)
@@ -193,8 +191,9 @@
 
       BugReport *report =
         new BugReport(*BT_undef, BT_undef->getDescription(), N);
-      report->addVisitor(bugreporter::getTrackNullOrUndefValueVisitor(N,
-                                        bugreporter::GetDerefExpr(N), report));
+      bugreporter::addTrackNullOrUndefValueVisitor(N,
+                                                   bugreporter::GetDerefExpr(N),
+                                                   report);
       report->disablePathPruning();
       C.EmitReport(report);
     }