1. the lio_sigsetup() method use a universal sighand instance across all
aiocb instances, but inside the lio_sighandler() method, if one aiocb is
handle finished, then this method will free the sighand instance that
come along with current aiocb instance. thus when handle next aiocb
instance, use-after-free crash will happen. in order to solve this
problem, we make each aiocb instance have their own sighand instance
2. make the lio_listio implementation can pass the
ltp/open_posix_testsuite/lio_listio testcases
3. the modification are referred to https://pubs.opengroup.org/onlinepubs/9699919799/functions/lio_listio.html
Signed-off-by: guoshichao <guoshichao@xiaomi.com>