initrd/cmdline: add support for rd.neednet option

This is used to indicate the network dracut module should fall back to
configure network automatically (as with ip=dhcp was specified) if
there's no other network configuration present on the command line.

The option is documented in dracut.cmdline(7).
12 jobs for lr/rd-neednet in 37 minutes and 26 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Test
passed #321682
allowed to fail
checkpatch

00:01:14

passed #321689
t_debian:9

00:20:53

passed #321691
t_debian:sid

00:18:43

manual #321690
allowed to fail manual
t_debian:testing
passed #321683
t_fedora:28

00:28:35

passed #321684
t_fedora:29

00:36:03

passed #321685
t_fedora:30

00:29:37

manual #321686
allowed to fail manual
t_fedora:rawhide
passed #321687
t_ubuntu:16.04

00:13:09

passed #321688
t_ubuntu:18.04

00:18:57

 
  External
failed NetworkManager test verification

failed NetworkManager test verification

06:00:02