busybox: simplify listing of supported utilities

'--list' option is supported since busybox-1.20.0, which was released
in 2010.

modules.d/05busybox/module-setup.sh

@@ -14,15 +14,16 @@ depends() {
 
 # called by dracut
 install() {
-    local _i _progs _path _busybox
+    local _i _path _busybox
+    local _progs=()
     _busybox=$(type -P busybox)
     inst $_busybox /usr/bin/busybox
-    for _i in $($_busybox | sed -ne '1,/Currently/!{s/,//g; s/busybox//g; p}')
-    do
-        _progs="$_progs $_i"
+    for _i in $($_busybox --list); do
+        [[ ${_i} == busybox ]] && continue
+        _progs+=("${_i}")
     done
 
-    for _i in $_progs; do
+    for _i in "${_progs[@]}"; do
         _path=$(find_binary "$_i")
         [ -z "$_path" ] && continue
         ln_r /usr/bin/busybox $_path