_rtld_allocate_tls
tls = _rtld_allocate_tls(NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN);
__weak_reference(__libc_allocate_tls, _rtld_allocate_tls);
void *_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign);
tcb = _rtld_allocate_tls(NULL, TLS_TCB_SIZE, TLS_TCB_ALIGN);
void *_rtld_allocate_tls(void *oldtls, size_t tcbsize, size_t tcbalign)