[glibc] Fix ifunc-impl-list.c build for s390

[Joseph Myers <jsm28@sourceware.org>]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=609054152fd77c9b572bb04c4af2f8da1ed0c86e

commit 609054152fd77c9b572bb04c4af2f8da1ed0c86e
Author: Joseph Myers <joseph@codesourcery.com>
Date:   Fri Feb 17 17:23:50 2023 +0000

    Fix ifunc-impl-list.c build for s390
    
    Builds for s390 recently started failing with:
    
    ../sysdeps/s390/multiarch/ifunc-impl-list.c: In function '__libc_ifunc_impl_list':
    ../sysdeps/s390/multiarch/ifunc-impl-list.c:83:21: error: unused variable 'dl_hwcap' [-Werror=unused-variable]
       83 |   unsigned long int dl_hwcap = features->hwcap;
          |                     ^~~~~~~~
    
    https://sourceware.org/pipermail/libc-testresults/2023q1/010855.html
    
    Add __attribute__ ((unused)) as already done for another variable
    there.
    
    Tested with build-many-glibcs.py (compilers and glibcs) for
    s390x-linux-gnu and s390-linux-gnu.
    
    Note: s390x-linux-gnu-O3 started failing with a different error
    earlier; that problem may still need to be fixed after this fix is in.
    
    https://sourceware.org/pipermail/libc-testresults/2023q1/010829.html

Diff:
---
 sysdeps/s390/multiarch/ifunc-impl-list.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/sysdeps/s390/multiarch/ifunc-impl-list.c b/sysdeps/s390/multiarch/ifunc-impl-list.c
index 1532258af2..faa428f9ab 100644
--- a/sysdeps/s390/multiarch/ifunc-impl-list.c
+++ b/sysdeps/s390/multiarch/ifunc-impl-list.c
@@ -80,7 +80,7 @@ __libc_ifunc_impl_list (const char *name, struct libc_ifunc_impl *array,
 
   /* Get hardware information.  */
   const struct cpu_features *features = &GLRO(dl_s390_cpu_features);
-  unsigned long int dl_hwcap = features->hwcap;
+  unsigned long int dl_hwcap __attribute__ ((unused)) = features->hwcap;
   const unsigned long long * __attribute__((unused)) stfle_bits
     = features->stfle_bits;