fix regression in dl_iterate_phdr reporting of modules with no TLS

__tls_get_addr should not be called with an invalid TLS module id of
0. in practice it probably "works", returning the DTV length as if it
were a pointer, and the callback should probably not inspect
dlpi_tls_data in this case, but it's likely that some real-world
callbacks use a check on dlpi_tls_data being non-null, rather than on
dlpi_tls_modid being nonzero, to conclude that the module has TLS.

ldso/dynlink.c

@@ -2331,7 +2331,8 @@ int dl_iterate_phdr(int(*callback)(struct dl_phdr_info *info, size_t size, void
 		info.dlpi_adds      = gencnt;
 		info.dlpi_subs      = 0;
 		info.dlpi_tls_modid = current->tls_id;
-		info.dlpi_tls_data = __tls_get_addr((tls_mod_off_t[]){current->tls_id,0});
+		info.dlpi_tls_data = !current->tls_id ? 0 :
+			__tls_get_addr((tls_mod_off_t[]){current->tls_id,0});
 
 		ret = (callback)(&info, sizeof (info), data);