C++: Fix experimental query that uses the deprecated freeCall predicate

Author: jketema

cpp/ql/src/experimental/Security/CWE/CWE-415/DoubleFree.ql

@@ -14,8 +14,8 @@ import cpp
 
 from FunctionCall fc, FunctionCall fc2, LocalScopeVariable v
 where
-  freeCall(fc, v.getAnAccess()) and
-  freeCall(fc2, v.getAnAccess()) and
+  fc.(DeallocationExpr).getFreedExpr() = v.getAnAccess() and
+  fc2.(DeallocationExpr).getFreedExpr() = v.getAnAccess() and
   fc != fc2 and
   fc.getASuccessor*() = fc2 and
   not exists(Expr exptmp |