remove redundant code in do_dlsym function

commit 637dd2d383 introduced the checks
for RTLD_DEFAULT and RTLD_NEXT here, claiming they fixed a regression,
but the above conditional block clearly already covered these cases,
and removing the checks produces no difference in the generated code.

src/ldso/dynlink.c

@@ -1500,7 +1500,7 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
 			return __tls_get_addr((size_t []){def.dso->tls_id, def.sym->st_value});
 		return def.dso->base + def.sym->st_value;
 	}
-	if (p != RTLD_DEFAULT && p != RTLD_NEXT && invalid_dso_handle(p))
+	if (invalid_dso_handle(p))
 		return 0;
 	if (p->ghashtab) {
 		gh = gnu_hash(s);