scripts: Re-added -q/--quiet to result scripts

I forgot that this is still useful for erroring scripts, such as
stack.py when checking for recursion.

Technically this is possible with -o/dev/null, but that's both
unnecessarily complicated and includes the csv encoding cost for no
reason.

scripts/csv.py

@@ -2374,7 +2374,7 @@ def main(csv_paths, *,
                 depth=depth,
                 **args)
     # print table
-    else:
+    elif not args.get('quiet'):
         table(Result, results, diff_results,
                 by=by,
                 fields=fields,
@@ -2402,6 +2402,10 @@ if __name__ == "__main__":
             '--help-exprs',
             action='store_true',
             help="Show what field exprs are available.")
+    parser.add_argument(
+            '-q', '--quiet',
+            action='store_true',
+            help="Don't show anything, useful when checking for errors.")
     parser.add_argument(
             '-o', '--output',
             help="Specify CSV file to store results.")