Add a feature test to test for CXX11 override

* Ref STEllAR-GROUP#2829

cmake/HPX_AddConfigTest.cmake

@@ -555,6 +555,14 @@ macro(hpx_check_for_cxx11_noreturn_attribute)
     FILE ${ARGN})
 endmacro()
 
+###############################################################################
+macro(hpx_check_for_cxx11_override)
+  add_hpx_config_test(HPX_WITH_CXX11_OVERRIDE
+    SOURCE cmake/tests/cxx11_override.cpp
+    FILE ${ARGN}
+    CMAKECXXFEATURE cxx_override)
+endmacro()
+
 ###############################################################################
 macro(hpx_check_for_cxx14_constexpr)
   add_hpx_config_test(HPX_WITH_CXX14_CONSTEXPR

cmake/HPX_PerformCxxFeatureTests.cmake

@@ -79,6 +79,9 @@ macro(hpx_perform_cxx_feature_tests)
   hpx_check_for_cxx11_variadic_templates(
     REQUIRED "HPX needs support for C++11 variadic templates")
 
+  hpx_check_for_cxx11_override(
+    REQUIRED "HPX needs support for C++11 override")
+
   # Check the availability of certain C++11 library features
   hpx_check_for_cxx11_std_array(
     REQUIRED "HPX needs support for C++11 std::array")

cmake/tests/cxx11_override.cpp

@@ -0,0 +1,29 @@
+////////////////////////////////////////////////////////////////////////////////
+//  Copyright (c) 2017 Denis Blank
+//
+//  Distributed under the Boost Software License, Version 1.0. (See accompanying
+//  file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+////////////////////////////////////////////////////////////////////////////////
+
+class my_base
+{
+  public:
+    my_base() { }
+    virtual ~my_base() { }
+
+    virtual void do_sth() { }
+};
+
+class my_inh : public my_base
+{
+  public:
+    my_inh() { }
+
+    void do_sth() override { }
+};
+
+int main()
+{
+    my_base* obj = new my_inh();
+    delete obj;
+}