[master] 89b393e76 print usage for the right reason

[Guillaume Quintard]

commit 89b393e76cd488d08cb22d68ca33661cdf10b475
Author: Guillaume Quintard <guillaume at varnish-software.com>
Date:   Wed Apr 28 21:42:54 2021 -0700

    print usage for the right reason

diff --git a/bin/varnishd/mgt/mgt_main.c b/bin/varnishd/mgt/mgt_main.c
index 9f4c23623..9ad6d8a7c 100644
--- a/bin/varnishd/mgt/mgt_main.c
+++ b/bin/varnishd/mgt/mgt_main.c
@@ -79,7 +79,7 @@ static struct vpf_fh *pfh2 = NULL;
 static struct vfil_path *vcl_path = NULL;
 static VTAILQ_HEAD(,f_arg) f_args = VTAILQ_HEAD_INITIALIZER(f_args);
 
-static const char opt_spec[] = "a:b:Cdf:Fh:i:I:j:l:M:n:P:p:r:S:s:T:t:VW:x:";
+static const char opt_spec[] = "?a:b:Cdf:Fh:i:I:j:l:M:n:P:p:r:S:s:T:t:VW:x:";
 
 int optreset;	// Some has it, some doesn't.  Cheaper than auto*