tools/nolibc: crt.h: initialize stack protector

As suggested by Thomas, It is able to move the stackprotector
initialization from the assembly _start to the beginning of the new
_start_c(). Let's call __stack_chk_init() in _start_c() as a
preparation.

Suggested-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/lkml/a00284a6-54b1-498c-92aa-44997fa78403@t-8ch.de/


Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>