main-loop: partial revert of 5e3bc73

This patch reverts part of 5e3bc735d93dd23f074b5116fd11e1ad8cd4962f.

Paolo Bonzini wrote this patch and commented:

"WSAEventSelect is edge-triggered and the event will not be signaled if
the socket handler does not consume all the data in the socket buffer."

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Message-id: 1368718561-7816-3-git-send-email-stefanha@redhat.com
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
