p4raw-id: //depot/perlext/Thread@97
+See the README.threads in the main perl 5.004_xx development
+distribution (x >= 50) for details of how to build and use this.
+If all else fails, read on.
+
If your version of patch can't create a file from scratch, then you'll
need to create an empty thread.h manually first. Perl itself will need
to be built with -DUSE_THREADS yet. If you're using MIT pthreads or