[binutils-gdb] fix gdb.base/access-mem-running.exp for clang testing

[Bruno Larsen]

https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=96ca89d245e262578ef565247c1d68dff493d8a3

commit 96ca89d245e262578ef565247c1d68dff493d8a3
Author: Bruno Larsen <blarsen@redhat.com>
Date:   Wed Jul 20 16:44:32 2022 -0300

    fix gdb.base/access-mem-running.exp for clang testing
    
    Clang was optimizing global_var away because it was not being used
    anywhere. this commit fixes that by adding the attribute used it.

Diff:
---
 gdb/testsuite/gdb.base/access-mem-running.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/gdb/testsuite/gdb.base/access-mem-running.c b/gdb/testsuite/gdb.base/access-mem-running.c
index 6335f1bf199..cff6f0da820 100644
--- a/gdb/testsuite/gdb.base/access-mem-running.c
+++ b/gdb/testsuite/gdb.base/access-mem-running.c
@@ -19,7 +19,7 @@
 
 static unsigned int global_counter = 1;
 
-static volatile unsigned int global_var = 123;
+static volatile unsigned int __attribute__((used)) global_var = 123;
 
 static void
 maybe_stop_here ()