[glibc/fw/glibc-hwcaps] aarch64: Add glibc-hwcaps support

[Florian Weimer]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=eec88dfcec8092033aac7c3b30268f437e6ad1ea

commit eec88dfcec8092033aac7c3b30268f437e6ad1ea
Author: Florian Weimer <fweimer@redhat.com>
Date:   Fri Jun 19 16:04:41 2020 +0200

    aarch64: Add glibc-hwcaps support
    
    At this point, only the "atomics" subdirectory is available,
    for libraries built using LSE atomics.

Diff:
---
 sysdeps/aarch64/dl-hwcaps-subdirs.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/sysdeps/aarch64/dl-hwcaps-subdirs.c b/sysdeps/aarch64/dl-hwcaps-subdirs.c
new file mode 100644
index 0000000000..fd6325024e
--- /dev/null
+++ b/sysdeps/aarch64/dl-hwcaps-subdirs.c
@@ -0,0 +1,31 @@
+/* Architecture-specific glibc-hwcaps subdirectories.  aarch64 version.
+   Copyright (C) 2020 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/>.  */
+
+#include <dl-hwcaps.h>
+#include <ldsodefs.h>
+
+const char _dl_hwcaps_subdirs[] = "atomics";
+
+int32_t
+_dl_hwcaps_subdirs_active (void)
+{
+  if (GLRO (dl_hwcap) & HWCAP_ATOMICS)
+    return 1;
+
+  return 0;
+}