tools/nolibc: x86_64: disable stack protector for _start

This was forgotten in the original submission.

It is unknown why it worked for x86_64 on some compiler without this
attribute.
Reported-by: Willy Tarreau <w@1wt.eu>
Closes: https://lore.kernel.org/lkml/20230520133237.GA27501@1wt.eu/
Fixes: 0d8c461a ("tools/nolibc: x86_64: add stackprotector support")
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

tools/include/nolibc/arch-x86_64.h

@@ -190,7 +190,7 @@ const unsigned long *_auxv __attribute__((weak));
  * 2) The deepest stack frame should be zero (the %rbp).
  *
  */
-void __attribute__((weak,noreturn,optimize("omit-frame-pointer"))) _start(void)
+void __attribute__((weak,noreturn,optimize("omit-frame-pointer"),no_stack_protector)) _start(void)
 {
 	__asm__ volatile (
 #ifdef NOLIBC_STACKPROTECTOR