Update dtach to 0.8.
Patch provided by MAINTAINER, Francis GUDIN.

The changes in version 0.8 are:
- When using dtach -A or dtach -c, the master will now wait until the client
  attaches before trying to read from the program being executed. This avoids
  a race condition when the program prints something and exits before the
  client can attach itself.
- Instead of exiting quietly, dtach will now report any errors that occur
  while trying to execute the program.
- dtach -n can now be used without a terminal.
- dtach -A will now try to detect and remove stale sockets.
- Removed a Linux-specific escape sequence from the code that restores the
  original terminal settings.
- Changed dtach.1 to use \- for the dashes in command line options, and
  fix an ambiguous backslash.
- Use non-blocking mode in the master process, and avoid data loss by ensuring
  that at least one attaching client succesfully completes a write.
- Fix -e ^<char> to work with lowercase characters.

(obache)