dselect: On --help print action names from the menuentries table

This unmarks those strings for translation, as they should not get
translated anyway, makes sure all actions will always be listed and
those will not get out of sync.

dselect/main.cc

@@ -195,10 +195,10 @@ usage(const struct cmdinfo *ci, const char *value)
 "  --version                  Show the version.\n"
 "\n"));
 
-  printf(_(
-"Actions:\n"
-"  access update select install config remove quit\n"
-"\n"));
+  printf(_("Actions:\n"));
+  for (i = 0; menuentries[i].command; i++)
+    printf("  %s", menuentries[i].command);
+  fputs("\n\n", stdout);
 
   printf(_("Screenparts:\n"));
   for (i=0; screenparttable[i].name; i++)