run_erl: Redirect standard streams to /dev/null

Like in epmd and erlexec. Otherwise "run_erl" fails on some platforms
when called with the "-daemon" option, printing this error:

  "Cannot dup"
Merge branch 'weisslj/run-erl-redirect-dev-null/OTP-11215' into maint

* weisslj/run-erl-redirect-dev-null/OTP-11215:
  run_erl: Redirect standard streams to /dev/null
Merge branch 'maint'