Currently test-io-channel-socket doesn't init with
qemu_init_main_loop
and that's cause the qemu_aio_context not inited,
and the following is the stack when null pointer accessed:

qemu_fd_register (c:\work\xemu\qemu\util\main-loop.c:336)
qemu_try_set_nonblock (c:\work\xemu\qemu\util\oslib-win32.c:224)
qemu_set_nonblock (c:\work\xemu\qemu\util\oslib-win32.c:230)
socket_can_bind_connect (c:\work\xemu\qemu\tests\socket-helpers.c:93)
socket_check_protocol_support (c:\work\xemu\qemu\tests\socket-helpers.c:141)
main (c:\work\xemu\qemu\tests\test-io-channel-socket.c:568)
__tmainCRTStartup (@__tmainCRTStartup:142)
mainCRTStartup (@1400014f6..140001539:3)
BaseThreadInitThunk (@BaseThreadInitThunk:9)
RtlUserThreadStart (@RtlUserThreadStart:12)

Signed-off-by: Yonggang Luo <luoyonggang@gmail.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200915121318.247-18-luoyonggang@gmail.com>
Signed-off-by: Thomas Huth <thuth@redhat.com>