savevm: un-export qemu_file_set_error()

Signed-off-by: Juan Quintela <quintela@redhat.com>

Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/savevm.c b/savevm.c
index e44bede..dee6899 100644
--- a/savevm.c
+++ b/savevm.c
@@ -440,7 +440,7 @@
     return f->last_error;
 }
 
-void qemu_file_set_error(QEMUFile *f, int ret)
+static void qemu_file_set_error(QEMUFile *f, int ret)
 {
     f->last_error = ret;
 }