throw_exception() now ensures that the exception type passed to it derives publicly from std::exception.

[SVN r45041]

test/Jamfile.v2

@@ -26,6 +26,7 @@ run errno_test.cpp ;
 run error_info_test.cpp ;
 run what_test.cpp ;
 compile-fail exception_fail.cpp ;
+compile-fail throw_exception_fail.cpp ;
 
 #headers
 compile enable_current_exception_hpp_test.cpp ;