C++: Use ConditionDeclExpr in AnalysedExpr::isDef

cpp/ql/lib/semmle/code/cpp/controlflow/Nullness.qll

@@ -171,7 +171,7 @@ class AnalysedExpr extends Expr {
     this.inCondition() and
     (
       this.(Assignment).getLValue() = v.getAnAccess() or
-      exists(Initializer i | this.getEnclosingStmt() = i.getEnclosingStmt() and v = i.getDeclaration())
+      this.(ConditionDeclExpr).getVariableAccess() = v.getAnAccess()
     )
   }