csu: Implement and use _dl_early_allocate during static startup

This implements mmap fallback for a brk failure during TLS
allocation.

scripts/tls-elf-edit.py is updated to support the new patching method.
The script no longer requires that in the input object is of ET_DYN
type.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

elf/tst-tls-allocation-failure-static.c

@@ -0,0 +1,31 @@
+/* Base for test program with impossiblyh large PT_TLS segment.
+   Copyright (C) 2022 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+/* The test actual binary is patched using scripts/tst-elf-edit.py
+   --maximize-tls-size, and this introduces the expected test
+   allocation failure due to an excessive PT_LS p_memsz value.
+
+   Patching the binary is required because on some 64-bit targets, TLS
+   relocations can only cover a 32-bit range, and glibc-internal TLS
+   variables such as errno end up outside that range.  */
+
+int
+main (void)
+{
+  return 0;
+}