Fall back to just hostname if hostname doesn't support -A (#900)

Only the Debian hostname program supports the -A option. Other ones
like the net-tools and coreutils hostname programs don't.

Author: twhitehead

lib/ood_core/job/adapters/linux_host/templates/script_wrapper.erb.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 SSH_HOSTS=(<%= ssh_hosts.join(' ').to_s %>)
-hostnames=`hostname -A`
+hostnames=`hostname -A 2>/dev/null || hostname`
 for host in ${SSH_HOSTS[@]}
 do
     if [[ " ${hostnames[@]} " =~ " ${host} " ]]; then

lib/ood_core/job/adapters/systemd/templates/script_wrapper.erb.sh

@@ -1,6 +1,6 @@
 #!/bin/bash
 SSH_HOSTS=(<%= ssh_hosts.join(' ').to_s %>)
-hostnames=`hostname -A`
+hostnames=`hostname -A 2>/dev/null || hostname`
 for host in ${SSH_HOSTS[@]}
 do
     if [[ " ${hostnames[@]} " =~ " ${host} " ]]; then