[6.0] b0b82f39e Ignore values non-positive values.

[Dridi Boukelmoune]

commit b0b82f39e6659118483b9d0022b95a7c39ff00c6
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Sun Sep 9 12:41:18 2018 +0000

    Ignore values non-positive values.
    
    Fixes:  #2773

diff --git a/bin/varnishhist/varnishhist.c b/bin/varnishhist/varnishhist.c
index 52bb69a6d..1ef81f15f 100644
--- a/bin/varnishhist/varnishhist.c
+++ b/bin/varnishhist/varnishhist.c
@@ -295,7 +295,7 @@ accumulate(struct VSL_data *vsl, struct VSL_transaction * const pt[],
 			}
 		}
 
-		if (skip || !match)
+		if (skip || !match || value <= 0)
 			continue;
 
 		/* select bucket */