Increment fetch_failed for all causes

IOW if we ended up in vcl_backend_error{} or failed after returning
delivery in vcl_backend_response{} (e.g. we did not receive enough bytes)
we will bump this counter.

Conflicts:
	bin/varnishd/cache/cache_fetch.c
	bin/varnishtest/tests/r01624.vtc
	include/tbl/vsc_f_main.h

bin/varnishd/cache/cache_fetch.c

@@ -687,6 +687,7 @@ vbf_stp_fetch(struct worker *wrk, struct busyobj *bo)
 			// XXX: doclose = ?
 			return (F_STP_ERROR);
 		} else {
+			wrk->stats->fetch_failed++;
 			return (F_STP_FAIL);
 		}
 	}
@@ -763,6 +764,7 @@ vbf_stp_condfetch(struct worker *wrk, struct busyobj *bo)
 		(void)VFP_Error(bo->vfc, "Template object failed");
 	if (bo->vfc->failed) {
 		VDI_Finish(bo->wrk, bo);
+		wrk->stats->fetch_failed++;
 		return (F_STP_FAIL);
 	}
 
@@ -799,6 +801,8 @@ vbf_stp_error(struct worker *wrk, struct busyobj *bo)
 	AN(bo->fetch_objcore->flags & OC_F_BUSY);
 	assert(bo->director_state == DIR_S_NULL);
 
+	wrk->stats->fetch_failed++;
+
 	now = W_TIM_real(wrk);
 	VSLb_ts_busyobj(bo, "Error", now);
 
@@ -899,7 +903,6 @@ vbf_stp_fail(struct worker *wrk, struct busyobj *bo)
 		EXP_Rearm(bo->fetch_objcore,
 		    bo->fetch_objcore->exp.t_origin, 0, 0, 0);
 	}
-	wrk->stats->fetch_failed++;
 	VBO_setstate(bo, BOS_FAILED);
 	return (F_STP_DONE);
 }

bin/varnishtest/tests/b00020.vtc

@@ -46,4 +46,4 @@ client c1 {
 
 varnish v1 -expect n_object == 1
 varnish v1 -expect n_objectcore == 1
-
+varnish v1 -expect fetch_failed == 1

bin/varnishtest/tests/b00023.vtc

@@ -17,7 +17,6 @@ client c1 {
 	expect resp.status == 503
 } -run
 
-
 server s1 {
 	rxreq
 	delay 0.5
@@ -29,3 +28,5 @@ client c1 {
 	rxresp
 	expect resp.status == 200
 } -run
+
+varnish v1 -expect fetch_failed == 1

bin/varnishtest/tests/b00038.vtc

@@ -35,3 +35,5 @@ client c1 {
 	rxresp
 	expect resp.status == 503
 } -run
+
+varnish v1 -expect fetch_failed == 1

bin/varnishtest/tests/c00061.vtc

@@ -22,3 +22,6 @@ client c1 {
 	rxresp
 	expect resp.status == 504
 } -run
+
+varnish v1 -expect backend_fail == 3
+varnish v1 -expect fetch_failed == 3

bin/varnishtest/tests/r01624.vtc

@@ -25,9 +25,10 @@ varnish v1 -vcl+backend {} -start
 
 client c1 {
 	txreq
+	rxresphdrs
+	expect resp.status == 200
 	non-fatal
-	timeout 3
-	rxresp
+	rxrespbody
 } -run
 
 delay .2
@@ -38,3 +39,5 @@ client c1 {
 	rxresp
 	expect resp.bodylen == 7
 } -run
+
+varnish v1 -expect fetch_failed == 1

bin/varnishtest/tests/r01648.vtc

@@ -73,3 +73,5 @@ client c3 {
 	expect resp.status == 200
 	expect resp.body == "abcdef"
 } -run
+
+varnish v1 -expect fetch_failed == 2

include/tbl/vsc_f_main.h

@@ -184,7 +184,7 @@ VSC_F(fetch_304,		uint64_t, 1, 'c', 'i', info,
 	"beresp with no body because of 304 response."
 )
 VSC_F(fetch_failed,		uint64_t, 1, 'c', 'i', info,
-    "Fetch failed (all causes), where we do get hold of the backend.",
+    "Fetch failed (all causes)",
 	"beresp fetch failed."
 )
 VSC_F(fetch_no_thread,		uint64_t, 1, 'c', 'i', info,