external/boost: silence some GCC 6 warnings

Change-Id: I4613f013c39e439dd11d3abc3737511cb8788d4f

external/boost/UnpackedTarball_boost.mk

@@ -86,6 +86,7 @@ boost_patches += boost_1_59_0.multi_array.wshadow.patch
 boost_patches += boost_1_59_0.property_tree.wreturn-type.patch
 
 boost_patches += clang-cl.patch.0
+boost_patches += gcc6-warnings.patch.0
 
 $(eval $(call gb_UnpackedTarball_UnpackedTarball,boost))
 

external/boost/gcc6-warnings.patch.0

+--- boost/function/function_base.hpp
++++ boost/function/function_base.hpp
+@@ -305,7 +305,14 @@
+           if (op == clone_functor_tag || op == move_functor_tag) {
+             const functor_type* in_functor = 
+               static_cast<const functor_type*>(static_cast<void*>(&in_buffer.data));
++#if defined __GNUC__
++#pragma GCC diagnostic push
++#pragma GCC diagnostic ignored "-Wplacement-new"
++#endif
+             new (reinterpret_cast<void*>(&out_buffer.data)) functor_type(*in_functor);
++#if defined __GNUC__
++#pragma GCC diagnostic pop
++#endif
+ 
+             if (op == move_functor_tag) {
+               functor_type* f = static_cast<functor_type*>(static_cast<void*>(&in_buffer.data));
+--- boost/function/function_template.hpp
++++ boost/function/function_template.hpp
+@@ -569,7 +569,14 @@
+         void 
+         assign_functor(FunctionObj f, function_buffer& functor, mpl::true_) const
+         {
++#if defined __GNUC__
++#pragma GCC diagnostic push
++#pragma GCC diagnostic ignored "-Wplacement-new"
++#endif
+           new (reinterpret_cast<void*>(&functor.data)) FunctionObj(f);
++#if defined __GNUC__
++#pragma GCC diagnostic pop
++#endif
+         }
+         template<typename FunctionObj,typename Allocator>
+         void 
+--- boost/multi_index/detail/index_node_base.hpp
++++ boost/multi_index/detail/index_node_base.hpp
+@@ -51,7 +51,14 @@
+ 
+   value_type& value()
+   {
++#if defined __GNUC__
++#pragma GCC diagnostic push
++#pragma GCC diagnostic ignored "-Wstrict-aliasing"
++#endif
+     return *reinterpret_cast<value_type*>(&this->space);
++#if defined __GNUC__
++#pragma GCC diagnostic pop
++#endif
+   }
+ 
+   const value_type& value()const