Raise only when different included blocks are defined

Perhaps, raise of error when module gets loaded twice isn't good

This happens when module files are loaded first time (e.g. while app reloading) and further required by hand (because some lib doesn't expect such preloading) - raise of error isn't - e.g. see ctran/annotate_models#181 for this case

See #10652 and #10650 for initial idea.
Also checked, that Proc#source_location works on jruby & rbx, too