Minor cleanup: use BuiltinBug (which will soon be renamed) for DeferenceChecker and friends so that they always report the same bug type.

llvm-svn: 86208
diff --git a/clang/lib/Analysis/UndefinedArgChecker.cpp b/clang/lib/Analysis/UndefinedArgChecker.cpp
index a229f55f..549c3b5 100644
--- a/clang/lib/Analysis/UndefinedArgChecker.cpp
+++ b/clang/lib/Analysis/UndefinedArgChecker.cpp
@@ -29,8 +29,8 @@
     if (C.getState()->getSVal(*I).isUndef()) {
       if (ExplodedNode *N = C.GenerateNode(CE, true)) {
         if (!BT)
-          BT = new BugType("Pass-by-value argument in function call is "
-                           "undefined", "Logic error");
+          BT = new BuiltinBug("Pass-by-value argument in function call is "
+                              "undefined");
         // Generate a report for this bug.
         EnhancedBugReport *R = new EnhancedBugReport(*BT, BT->getName().c_str(),
                                                      N);