[glibc/maskray/clang] x86_64: Add memcmpeq.S to fix disable-multi-arch build

[glibc/maskray/clang] x86_64: Add memcmpeq.S to fix disable-multi-arch build

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=1d56fd3baeaa67405b8a1d67275b4c6eecac77b8

commit 1d56fd3baeaa67405b8a1d67275b4c6eecac77b8
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Thu Oct 28 14:41:03 2021 -0500

    x86_64: Add memcmpeq.S to fix disable-multi-arch build
    
    The following commit:
    
        commit cf4fd28ea453d1a9cec93939bc88b58ccef5437a
        Author: Noah Goldstein <goldstein.w.n@gmail.com>
        Date:   Tue Oct 26 19:43:18 2021 -0500
    
    Broke --disable-multi-arch build for x86_64 because x86_64/memcmpeq.S
    was not defined outside of multiarch and the alias for __memcmpeq in
    x86_64/memcmp.S was removed.
    
    This commit fixes that issue by adding x86_64/memcmpeq.S.
    
    make xcheck passes on x86_64 with and without --disable-multi-arch

Diff:
---
 sysdeps/x86_64/memcmpeq.S | 21 +++++++++++++++++++++
 1 file changed, 21 insertions(+)

diff --git a/sysdeps/x86_64/memcmpeq.S b/sysdeps/x86_64/memcmpeq.S
new file mode 100644
index 0000000000..db1756915d
--- /dev/null
+++ b/sysdeps/x86_64/memcmpeq.S
@@ -0,0 +1,21 @@
+/* __memcmpeq optimized with SSE2.
+   Copyright (C) 2017-2021 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/>.  */
+
+#define memcmp	__memcmpeq
+#define USE_AS_MEMCMPEQ	1
+#include "multiarch/memcmp-sse2.S"