BUG/MINOR: wurfl: Fix HTX message prefetch

An additional argument has been added to smp_prefetch_htx() function in the
commit 778f5ed47 ("MEDIUM: checks/http-fetch: Support htx prefetch from a check
for HTTP samples"). But forgot to update call in wurfl module.

No need to backport.
diff --git a/src/wurfl.c b/src/wurfl.c
index 47968e2..b8133ba 100644
--- a/src/wurfl.c
+++ b/src/wurfl.c
@@ -436,7 +436,7 @@
 	ha_wurfl_log("WURFL: starting ha_wurfl_get_all\n");
 
 	chn = (smp->strm ? &smp->strm->req : NULL);
-	htx = smp_prefetch_htx(smp, chn, 1);
+	htx = smp_prefetch_htx(smp, chn, NULL, 1);
 	if (!htx)
 		return 0;
 
@@ -522,7 +522,7 @@
 	ha_wurfl_log("WURFL: starting ha_wurfl_get\n");
 
 	chn = (smp->strm ? &smp->strm->req : NULL);
-	htx = smp_prefetch_htx(smp, chn, 1);
+	htx = smp_prefetch_htx(smp, chn, NULL, 1);
 	if (!htx)
 		return 0;
 
@@ -739,7 +739,7 @@
 	// We could skip this chek since ha_wurfl_retrieve_header is called from inside
 	// ha_wurfl_get()/ha_wurfl_get_all() that already perform the same check
 	// We choose to keep it in case ha_wurfl_retrieve_header will be called directly
-	htx = smp_prefetch_htx(smp, chn, 1);
+	htx = smp_prefetch_htx(smp, chn, NULL, 1);
 	if (!htx) {
 		return NULL;
 	}