Fix 'config.py set' without --force
The `set` command can act on any known symbol.
diff --git a/scripts/config.py b/scripts/config.py
index 3b2aa63..1a2b159 100755
--- a/scripts/config.py
+++ b/scripts/config.py
@@ -384,7 +384,7 @@
sys.stdout.write(value + '\n')
return args.symbol not in config
elif args.command == 'set':
- if not args.force and args.symbol not in config:
+ if not args.force and args.symbol not in config.settings:
sys.stderr.write("A #define for the symbol {} "
"was not found in {}"
.format(args.symbol, args.file))