[6.0] e5238678c Flexelinting: Avoid stuff which looks like trigraphs

[Dridi Boukelmoune]

commit e5238678c3e6d6dffbf632a60365234510e008f5
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Thu Oct 3 09:04:12 2019 +0000

    Flexelinting:  Avoid stuff which looks like trigraphs

diff --git a/bin/varnishd/cache/cache_panic.c b/bin/varnishd/cache/cache_panic.c
index 3a37ea65b..4626eaaf2 100644
--- a/bin/varnishd/cache/cache_panic.c
+++ b/bin/varnishd/cache/cache_panic.c
@@ -612,7 +612,7 @@ pan_backtrace(struct vsb *vsb)
 		unw_get_reg(&cursor, UNW_REG_SP, &sp);
 		unw_get_proc_name(&cursor, fname, sizeof(fname), &offp);
 		VSB_printf(vsb, "ip=0x%lx, sp=0x%lx <%s+0x%lx>\n", (long) ip,
-		    (long) sp, fname[0] ? fname : "???", offp);
+		    (long) sp, fname[0] ? fname : "<unknown>", offp);
 	}
 
 	VSB_indent(vsb, -2);