Don't attempt to allocate a V1L from the workspace if it is overflowed.

Fixes:	#1796
Also triggered by:	The Wemm-Field

bin/varnishd/http1/cache_http1_deliver.c

@@ -112,10 +112,12 @@ V1D_Deliver(struct req *req, struct busyobj *bo, int sendbody)
 	if (sendbody && req->resp_len != 0)
 		VDP_push(req, v1d_bytes, NULL, 1);
 
+	AZ(req->wrk->v1l);
 	V1L_Reserve(req->wrk, req->ws, &req->sp->fd, req->vsl, req->t_prev);
 
 	if (WS_Overflowed(req->ws)) {
 		v1d_error(req, "workspace_client overflow");
+		AZ(req->wrk->v1l);
 		return;
 	}
 
@@ -134,5 +136,6 @@ V1D_Deliver(struct req *req, struct busyobj *bo, int sendbody)
 
 	if ((V1L_FlushRelease(req->wrk) || ois != OIS_DONE) && req->sp->fd >= 0)
 		SES_Close(req->sp, SC_REM_CLOSE);
+	AZ(req->wrk->v1l);
 	VDP_close(req);
 }

bin/varnishd/http1/cache_http1_line.c

@@ -78,6 +78,8 @@ V1L_Reserve(struct worker *wrk, struct ws *ws, int *fd, struct vsl_log *vsl,
 	CHECK_OBJ_NOTNULL(wrk, WORKER_MAGIC);
 	AZ(wrk->v1l);
 
+	if (WS_Overflowed(ws))
+		return;
 	res = WS_Snapshot(ws);
 	v1l = WS_Alloc(ws, sizeof *v1l);
 	if (v1l == NULL)