build: separate package identity from storage paths

cmd/wcc/check.c

@@ -82,9 +82,8 @@ resolve_typename(Checker *c, Node *n)
 		 * same name as the module itself (e.g. `random.random`). */
 		const char *dot = strrchr(nm, '.');
 		if (dot) {
-			char head[128] = {0};
 			size_t hl = (size_t)(dot - nm);
-			if (hl < sizeof head) memcpy(head, nm, hl);
+			char *head = astrndup(c->a, nm, hl);
 			Sym *m = scope_lookup(c->cur, head);
 			if (m && (m->kind == SK_USE || m->use_alias)) {
 				/* M1 #22: map the qualifier alias to its dotted