systemctl: obey --state in list-unit-files

(cherry picked from commit fec1530e6b)

Conflicts:
	src/systemctl/systemctl.c

src/systemctl/systemctl.c

@@ -777,6 +777,11 @@ static int compare_unit_file_list(const void *a, const void *b) {
 static bool output_show_unit_file(const UnitFileList *u) {
         const char *dot;
 
+        if (!strv_isempty(arg_states)) {
+                if (!strv_find(arg_states, unit_file_state_to_string(u->state)))
+                        return false;
+        }
+
         return !arg_types || ((dot = strrchr(u->path, '.')) && strv_find(arg_types, dot+1));
 }