[glibc/maskray/clang] String: Add __memcmpeq as build target

[glibc/maskray/clang] String: Add __memcmpeq as build target

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=3592ccd472a47ec8be977b0ff33f841f4c175caf

commit 3592ccd472a47ec8be977b0ff33f841f4c175caf
Author: Noah Goldstein <goldstein.w.n@gmail.com>
Date:   Tue Oct 26 19:42:59 2021 -0500

    String: Add __memcmpeq as build target
    
    No bug. This commit just adds __memcmpeq as a build target so that
    implementations for __memcmpeq that are not just aliases to memcmp can
    be supported.

Diff:
---
 string/Makefile   |  2 +-
 string/memcmpeq.c | 24 ++++++++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)

diff --git a/string/Makefile b/string/Makefile
index 40d6fac133..2199dd30b7 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -34,7 +34,7 @@ routines	:= strcat strchr strcmp strcoll strcpy strcspn		\
 		   strerror _strerror strlen strnlen			\
 		   strncat strncmp strncpy				\
 		   strrchr strpbrk strsignal strspn strstr strtok	\
-		   strtok_r strxfrm memchr memcmp memmove memset	\
+		   strtok_r strxfrm memchr memcmp memcmpeq memmove memset	\
 		   mempcpy bcopy bzero ffs ffsll stpcpy stpncpy		\
 		   strcasecmp strncase strcasecmp_l strncase_l		\
 		   memccpy memcpy wordcopy strsep strcasestr		\
diff --git a/string/memcmpeq.c b/string/memcmpeq.c
new file mode 100644
index 0000000000..08726325a8
--- /dev/null
+++ b/string/memcmpeq.c
@@ -0,0 +1,24 @@
+/* Copyright (C) 1991-2021 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/>.  */
+
+/* This file is intentionally left empty.  It exists so that both
+   architectures which implement __memcmpeq seperately from memcmp and
+   architectures which implement __memcmpeq by having it alias memcmp will
+   build.
+
+   The alias for __memcmpeq to memcmp for the C implementation is in
+   memcmp.c.  */