vcc_err_unref=false should also allow unreferenced subroutines.

Submitted by:	ehocdet

Fixes	#911

bin/varnishtest/tests/r00911.vtc

+varnishtest "vcc_err_unref should also cover subs"
+
+server s1 {
+	rxreq
+	expect req.url == "/bar"
+	txresp -body "foobar"
+} -start
+
+varnish v1 -arg "-p vcc_err_unref=false" -vcl+backend { 
+	sub foobar {
+		set req.http.foobar = "foobar";
+	}
+} -start
+
+client c1 {
+	txreq  -url /bar
+	rxresp 
+	expect resp.http.content-length == 6
+	expect resp.bodylen == 6
+} -run

lib/libvcl/vcc_xref.c

@@ -292,6 +292,10 @@ vcc_checkaction2(struct vcc *tl, const struct symbol *sym)
 		return;
 	vsb_printf(tl->sb, "Function unused\n");
 	vcc_ErrWhere(tl, p->name);
+	if (!tl->err_unref) {
+		vsb_printf(tl->sb, "(That was just a warning)\n");
+		tl->err = 0;
+	}
 }
 
 int