[Bug sanitizer/57316] [4.8/4.9 regression] build failure in libsanitizer

[jakub at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57316

--- Comment #16 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Sorry for not catching it earlier, I'm worried about -Wunused complaining about
the vars.  Can you instead use something like
int x = syscall (__NR_gettid);
syscall (__NR_futex, &x, 1, 1);
syscall (__NR_exit_group, 0);
?  Please post to gcc-patches with the change (if it works).  Thanks.