Downstream-only patch to enhance CPU detection.  Review thread:

  <https://sourceware.org/pipermail/libc-alpha/2021-May/125916.html>

Author: Florian Weimer <fweimer@redhat.com>
Date:   Thu May 6 11:54:52 2021 +0200

    elf: Add hook for checking HWCAP bits after auxiliary vector parsing

diff --git a/elf/dl-sysdep.c b/elf/dl-sysdep.c
index 0658c17da632efa5..657d74597e64045f 100644
--- a/elf/dl-sysdep.c
+++ b/elf/dl-sysdep.c
@@ -46,6 +46,7 @@
 
 #include <dl-tunables.h>
 #include <dl-auxv.h>
+#include <dl-hwcap-check.h>
 
 extern char **_environ attribute_hidden;
 extern char _end[] attribute_hidden;
@@ -182,6 +183,8 @@ _dl_sysdep_start (void **start_argptr,
       DL_PLATFORM_AUXV
       }
 
+  dl_hwcap_check ();
+
 #ifndef HAVE_AUX_SECURE
   if (seen != -1)
     {
diff --git a/sysdeps/generic/dl-hwcap-check.h b/sysdeps/generic/dl-hwcap-check.h
new file mode 100644
index 0000000000000000..8db7a86256c9c724
--- /dev/null
+++ b/sysdeps/generic/dl-hwcap-check.h
@@ -0,0 +1,28 @@
+/* Check for hardware capabilities after HWCAP parsing.  Generic version.
+   Copyright (C) 2021 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/>.  */
+
+#ifndef _DL_HWCAP_CHECK_H
+#define _DL_HWCAP_CHECK_H
+
+static inline void
+dl_hwcap_check (void)
+{
+  /* The generic implementation does not perform any checks.  */
+}
+
+#endif /* _DL_HWCAP_CHECK_H */