rust fix for netbsd-8

["Gary Duzan" <gary%duzan.org@localhost>]

   Can the pthread_attr fix for rust mentioned in
http://mail-index.netbsd.org/pkgsrc-users/2017/08/03/msg025409.html
be pulled up to netbsd-8? I'm getting the same thing there, and
rust is required for the latest firefox.

   Thanks.

				Gary Duzan