nptl/sysdeps/generic not activated

[Roland McGrath]

Yeah, I think we knew that.  The couple of files there are probably way out
of date with respect to the API the real files should define, too, which is
lame since they really only exist as documentation for what you need to write.

If those files should be used at all, it should be done by the generic
configure code for all add-ons.  So far there has not really been any
add-on that had sysdeps/generic files that would really get used.