[glibc] elf: Fix tst-nodelete-dlclose-dso.c on clang-23

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=91d60ade97768eb419493ab340818c5716405d33

commit 91d60ade97768eb419493ab340818c5716405d33
Author: Adhemerval Zanella <[email protected]>
Date:   Tue Aug 11 14:28:58 2026 -0300

    elf: Fix tst-nodelete-dlclose-dso.c on clang-23
    
    clang-23 enables -Wunused-but-set-global by default, which flags
    variables that are set but never read.

Diff:
---
 elf/tst-nodelete-dlclose-dso.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/elf/tst-nodelete-dlclose-dso.c b/elf/tst-nodelete-dlclose-dso.c
index 252858e6c9..45bffc825e 100644
--- a/elf/tst-nodelete-dlclose-dso.c
+++ b/elf/tst-nodelete-dlclose-dso.c
@@ -29,8 +29,6 @@
 
 /* Plugin to load.  */
 static void *plugin_lib = NULL;
-/* Plugin function.  */
-static void (*plugin_func) (void);
 #define LIB_PLUGIN "tst-nodelete-dlclose-plugin.so"
 
 /* This function is never called but the plugin references it.
@@ -55,7 +53,7 @@ primary (void)
     }
   dlerror ();
 
-  plugin_func = (void (*) (void)) dlsym (plugin_lib, "plugin_func");
+  dlsym (plugin_lib, "plugin_func");
   error = dlerror ();
   if (error != NULL)
     {