Hide gdb info header from test.py/bench.py --gdb

This was too noisy when intermingled with other debug output
test.py/bench.py prints when dropping into gdb.

scripts/bench.py

@@ -1388,6 +1388,7 @@ def run(runner, bench_ids=[], **args):
             # can be helpful
             path, lineno = find_path(runner, failure.id, **args)
             cmd[:0] = args['gdb_path'] + [
+                '-q',
                 '-ex', 'break main',
                 '-ex', 'break %s:%d' % (path, lineno),
                 '-ex', 'run',
@@ -1395,17 +1396,20 @@ def run(runner, bench_ids=[], **args):
         elif args.get('gdb_perm'):
             path, lineno = find_path(runner, failure.id, **args)
             cmd[:0] = args['gdb_path'] + [
+                '-q',
                 '-ex', 'break %s:%d' % (path, lineno),
                 '-ex', 'run',
                 '--args']
         elif failure.assert_ is not None:
             cmd[:0] = args['gdb_path'] + [
+                '-q',
                 '-ex', 'run',
                 '-ex', 'frame function raise',
                 '-ex', 'up 2',
                 '--args']
         else:
             cmd[:0] = args['gdb_path'] + [
+                '-q',
                 '-ex', 'run',
                 '--args']