[master] c718adc4e varnishncsa: Fall time_firstbyte back to "missing int"

[Dridi Boukelmoune]

commit c718adc4ea935a8e7d8a393e18d5b6878164ed96
Author: Dridi Boukelmoune <dridi.boukelmoune at gmail.com>
Date:   Wed Sep 1 16:28:11 2021 +0200

    varnishncsa: Fall time_firstbyte back to "missing int"
    
    Fixes #3682

diff --git a/bin/varnishncsa/varnishncsa.c b/bin/varnishncsa/varnishncsa.c
index 9c9faf8f6..9ae918b0e 100644
--- a/bin/varnishncsa/varnishncsa.c
+++ b/bin/varnishncsa/varnishncsa.c
@@ -607,7 +607,7 @@ parse_x_format(char *buf)
 	int slt;
 
 	if (!strcmp(buf, "Varnish:time_firstbyte")) {
-		addf_fragment(&CTX.frag[F_ttfb], "");
+		addf_fragment(&CTX.frag[F_ttfb], CTX.missing_int);
 		return;
 	}
 	if (!strcmp(buf, "Varnish:hitmiss")) {