bash-completion: use builtins when generating list

awk is an external program, and it is better to stick to shell built-ins.

Also, even with external awk, sort -u is redundant, because the shell does
this on its own.

shell-completion/bash/networkctl

@@ -24,7 +24,7 @@ __contains_word () {
 }
 
 __get_links() {
-        networkctl list --no-legend --no-pager --all | awk '{ print $2 }' | sort -u
+        networkctl list --no-legend --no-pager --all | { while read -r a b c; do echo " $b"; done; };
 }
 
 _networkctl() {