tools/nolibc: x86-64: Update System V ABI document link

The old link no longer works, update it.
Acked-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/arch-x86_64.h

@@ -61,7 +61,7 @@ struct sys_stat_struct {
  *   - see also x86-64 ABI section A.2 AMD64 Linux Kernel Conventions, A.2.1
  *     Calling Conventions.
  *
- * Link x86-64 ABI: https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/x86-64-psABI
+ * Link x86-64 ABI: https://gitlab.com/x86-psABIs/x86-64-ABI/-/wikis/home
  *
  */