initialialize some ivars in ctor.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62700 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/APValue.h

@@ -54,6 +54,7 @@ private:
   struct Vec {
     APValue *Elts;
     unsigned NumElts;
+    Vec() : Elts(0), NumElts(0) {}
     ~Vec() { delete[] Elts; }
   };