qemu-sockets: Add error to non-blocking connect handler

An error value here would be quite handy and more consistent
with the rest of the code.

Signed-off-by: Corey Minyard <cminyard@mvista.com>
[Make sure SO_ERROR value is passed to error_setg_errno. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/migration-unix.c b/migration-unix.c
index 0a5f8a1..1cdadfb 100644
--- a/migration-unix.c
+++ b/migration-unix.c
@@ -33,12 +33,12 @@
     do { } while (0)
 #endif
 
-static void unix_wait_for_connect(int fd, void *opaque)
+static void unix_wait_for_connect(int fd, Error *err, void *opaque)
 {
     MigrationState *s = opaque;
 
     if (fd < 0) {
-        DPRINTF("migrate connect error\n");
+        DPRINTF("migrate connect error: %s\n", error_get_pretty(err));
         s->file = NULL;
         migrate_fd_error(s);
     } else {