Since this test is a 'dg-do run', it requires tls_runtime rather than
just tls.
This makes the test UNSUPPORTED on targets such as arm-non-eabi,
instead of FAIL/UNRESOLVED because __aeabi_read_tp is not provided
(e.g. when GCC is configured with --enable-threads=no.
gcc/testsuite/ChangeLog:
* g++.dg/cpp2a/decomp2.C: Require tls_runtime.
// P1091R3
// { dg-do run { target c++11 } }
// { dg-options "" }
-// { dg-require-effective-target tls }
+// { dg-require-effective-target tls_runtime }
// { dg-add-options tls }
namespace std {