Make BOOST_TEST_EQ/NE work with nullptr

include/boost/core/lightweight_test.hpp

@@ -25,6 +25,7 @@
 #include <boost/core/no_exceptions_support.hpp>
 #include <iostream>
 #include <cstring>
+#include <cstddef>
 
 //  IDE's like Visual Studio perform better if output goes to std::cout or
 //  some other stream, so allow user to configure output stream:
@@ -113,6 +114,10 @@ inline const void* test_output_impl(unsigned char* v) { return v; }
 inline const void* test_output_impl(signed char* v) { return v; }
 template<class T> inline const void* test_output_impl(T volatile* v) { return const_cast<T*>(v); }
 
+#if !defined( BOOST_NO_CXX11_NULLPTR )
+inline const void* test_output_impl(std::nullptr_t v) { return v; }
+#endif
+
 template<class T, class U> inline void test_eq_impl( char const * expr1, char const * expr2,
   char const * file, int line, char const * function, T const & t, U const & u )
 {