Add Polymorphic Memory Resource utilities and rework the separately compiled library:

- Dlmalloc's based C function are boost_cont_xxx no longer exported, but wrapped into C++ linkage dlmalloc_xxx functions to effectively reuse Boost's dynamic library and autolink machinery instead of rewriting machinery to compile the C source file.
- Refactored scoped_allocator_adaptor's construct logic as it was shared with polymorphic allocator's one. Moved common logic to detail/dispatch_uses_allocator.hpp. Refactored also scoped_allocator_adaptor test utilities to be reused with polymorphic_allocator tests.

test/pmr_set_test.cpp

@@ -0,0 +1,26 @@
+//////////////////////////////////////////////////////////////////////////////
+//
+// (C) Copyright Ion Gaztanaga 2015-2015. 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)
+//
+// See http://www.boost.org/libs/container for documentation.
+//
+//////////////////////////////////////////////////////////////////////////////
+
+#include <boost/container/pmr/set.hpp>
+#include <boost/static_assert.hpp>
+#include <boost/container/detail/type_traits.hpp>
+
+int main()
+{
+   using namespace boost::container;
+   using boost::container::container_detail::is_same;
+
+   typedef set<int, std::less<int>, pmr::polymorphic_allocator<int> > intcontainer_t;
+   BOOST_STATIC_ASSERT(( is_same<intcontainer_t, pmr::set_of<int>::type >::value ));
+   #if !defined(BOOST_NO_CXX11_TEMPLATE_ALIASES)
+      BOOST_STATIC_ASSERT(( is_same<intcontainer_t, pmr::set<int> >::value ));
+   #endif
+   return 0;
+}