util: Removed unused statement from FreeBSD build

Statement (void*)debug_name when FreeBSD is defined has no use. Removed
it to fix compiler warnings.

Signed-off-by: Eleni Maria Stea <elene.mst@gmail.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/11203>

src/util/anon_file.c

@@ -116,7 +116,6 @@ os_create_anonymous_file(off_t size, const char *debug_name)
 {
    int fd, ret;
 #ifdef __FreeBSD__
-   (void*)debug_name;
    fd = shm_open(SHM_ANON, O_CREAT | O_RDWR | O_CLOEXEC, 0600);
 #elif defined(__OpenBSD__)
    char template[] = "/tmp/mesa-XXXXXXXXXX";