Fix relay_old implementation of fsize_max and fnum_max.

Fix relay_old implementation of fsize_max and fnum_max.

With old relayfs, out_fd is used only when non-bulk mode. However,
open_oldoutfile and open_relayfs_files open files with fopen and
set only percpu_tmpfile. This will cause a problem with -S option,
that out_fd will be closed when the file size reaches fsize_max
and new fd will be opened only on percpu_tmpfile.

So, out_fd should be synchronized with percpu_tmpfile.

* runtime/staprun/relay_old.c (open_oldoutfile): Set fd of output file
  to out_fd[cpu].
  (open_relayfs_files): Ditto.