qemu-coroutine-io: fix for Win32

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
diff --git a/nbd.c b/nbd.c
index e7d1cee..5c28f71 100644
--- a/nbd.c
+++ b/nbd.c
@@ -156,7 +156,7 @@
             err = socket_error();
 
             /* recoverable error */
-            if (err == EINTR || (offset > 0 && err == EAGAIN)) {
+            if (err == EINTR || (offset > 0 && (err == EAGAIN || err == EWOULDBLOCK))) {
                 continue;
             }