Fix libc errno return for multiple system calls

[rennergade]

I've found a bug with errnos that may be prevalent for multiple system calls. I found this while testing the poll() call in a situation where we should return an errno. In this case it was EINTR which should return -1 and set the errno appropriately to 4.

Here we appropriately return -4 from lind_poll and NaClSysPoll .

But [here](static int nacl_irt_poll_lind (struct pollfd *fds, nfds_t nfds, int timeout)
{
int rv = NACL_SYSCALL (poll) (fds, nfds, timeout);
if (rv < 0)
return -rv;
return rv;
}) when we return to the IRT we negate the return value if its negative.

Then here in [poll.c](https://github.com/Lind-Project/Lind-GlibC/blob/5f73bc6e9b451a2bcef24f6967ece7fbedc41da2/sysdeps/nacl/poll.c#L10 it negates the errno again.

This ends up incorrectly setting the errno and the return value. poll() thinks were returning a non-error value of 4.

I think most of this code is a remnant of changes even before my time, and may be happening for a number of syscalls. We should comb through this code and do some tests to see what syscalls are affected when returning errors and fix those.

@yizhuoliang @Yaxuan-w can you address this as a project while I'm away?

If you have any questions about how the libc functions work @RusherRG and @kuzeyardabulut should be able to answer most questions.

[rennergade]

@Yaxuan-w fixed most of these but theres a few other ones left. This possibly could be an issue for @abunav6 to finish up.

[Yaxuan-w]

Here're list of syscalls need to be checked:

__nacl_irt_exit
__nacl_irt_gettod
__nacl_irt_clock
__nacl_irt_nanosleep
__nacl_irt_sched_yield
__nacl_irt_sysconf
__nacl_irt_chdir
__nacl_irt_chmod
__nacl_irt_getuid
__nacl_irt_geteuid
__nacl_irt_getgid
__nacl_irt_getegid
__nacl_irt_getcwd
__nacl_irt_fcntl_get
__nacl_irt_fcntl_set
__nacl_irt_ioctl
__nacl_irt_poll
__nacl_irt_ppoll
__nacl_irt_recvfrom
__nacl_irt_select
__nacl_irt_pselect
__nacl_irt_getdents
__nacl_irt_sysbrk
__nacl_irt_dyncode_create
__nacl_irt_dyncode_modify
__nacl_irt_dyncode_delete
__nacl_irt_thread_create
__nacl_irt_thread_exit
__nacl_irt_thread_nice
__nacl_irt_mutex_create
__nacl_irt_mutex_destroy
__nacl_irt_mutex_lock
__nacl_irt_mutex_unlock
__nacl_irt_mutex_trylock
__nacl_irt_cond_create
__nacl_irt_cond_destroy
__nacl_irt_cond_signal
__nacl_irt_cond_broadcast
__nacl_irt_cond_wait
__nacl_irt_cond_timed_wait_abs
__nacl_irt_tls_init
__nacl_irt_tls_get
__nacl_irt_open_resource
__nacl_irt_clock_getres
__nacl_irt_clock_gettime
__nacl_irt_gethostname
__nacl_irt_getpid
__nacl_irt_getppid
__nacl_irt_fork
__nacl_irt_dup
__nacl_irt_dup2
__nacl_irt_dup3
__nacl_irt_waitpid
__nacl_irt_wait
__nacl_irt_wait4
__nacl_irt_pipe
__nacl_irt_pipe2
__nacl_irt_execve
__nacl_irt_execv
__nacl_irt_sigprocmask
__nacl_irt_flock