vcc: return no symbol when types don't match

When we are looking for ! SYM_NONE and find ! SYM_NONE, do not
return the symbol we found.

The semantics of (kind != SYM_NONE && sym->kind != kind) are
inclusive because the next conditional is not true for this case.

Ref: 9d81a71a

Fixes: #2497

bin/varnishtest/tests/v00016.vtc

@@ -88,3 +88,17 @@ varnish v1 -errvcl {resolves to too many addresses} {
 		if (remote.ip == "varnish-cache.org") {}
 	}
 }
+
+varnish v1 -errvcl {Undefined acl foo} {
+	import directors;
+	backend b { .host = "127.0.0.1"; }
+
+	sub vcl_init {
+		new foo = directors.shard();
+	}
+	sub vcl_recv {
+		if (client.ip ~ foo) {
+			return (synth(200));
+		}
+	}
+}

lib/libvcc/vcc_symb.c

@@ -146,8 +146,9 @@ VCC_Symbol(struct vcc *tl, struct symbol *parent,
 			continue;
 		if (q < e)
 			break;
-		if (kind != SYM_NONE && sym->kind != kind)
-			break;
+		if (kind != SYM_NONE && sym->kind != SYM_NONE &&
+		    kind != sym->kind)
+			sym = NULL;
 		if (kind == SYM_NONE && sym->kind == kind)
 			continue;
 		break;