SO_ERROR is used to report asynchronous errors that are the result
of events within the network stack and not synchronous errors that
are the result of a library call(send/recv/connect)
Synchronous results are reported via errno.
Linux Programmer's Manual
...
NAME
getsockopt, setsockopt - get and set options on sockets
...
RETURN VALUE
...
On error, -1 is returned, and errno is set appropriately
Change-Id: I1a1a05a684dff8672aaf47eabee157ac0d275c2d
Signed-off-by: chao.an <anchao@xiaomi.com>