migration: Allow migrate_fd_connect to take an Error *

Allow whatever is performing the connection to pass migrate_fd_connect
an error to indicate there was a problem during connection, an allow
us to clean up.

The caller must free the error.

Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
diff --git a/migration/migration.h b/migration/migration.h
index 786d971..d3b214e 100644
--- a/migration/migration.h
+++ b/migration/migration.h
@@ -190,7 +190,7 @@
 void migrate_set_error(MigrationState *s, const Error *error);
 void migrate_fd_error(MigrationState *s, const Error *error);
 
-void migrate_fd_connect(MigrationState *s);
+void migrate_fd_connect(MigrationState *s, Error *error_in);
 
 MigrationState *migrate_init(void);
 bool migration_is_blocked(Error **errp);