Use defined-at-zero behavior for CLZ/CTZ builtins on PowerPC.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149181 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Basic/Targets.cpp b/lib/Basic/Targets.cpp
index a557142..5cdb36f 100644
--- a/lib/Basic/Targets.cpp
+++ b/lib/Basic/Targets.cpp
@@ -572,6 +572,8 @@
     NumRecords = clang::PPC::LastTSBuiltin-Builtin::FirstTSBuiltin;
   }
 
+  virtual bool isCLZForZeroUndef() const { return false; }
+
   virtual void getTargetDefines(const LangOptions &Opts,
                                 MacroBuilder &Builder) const;