stubs: fully replace qemu-tool.c and qemu-user.c

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/stubs/iothread-lock.c b/stubs/iothread-lock.c
new file mode 100644
index 0000000..5d8aca1
--- /dev/null
+++ b/stubs/iothread-lock.c
@@ -0,0 +1,10 @@
+#include "qemu-common.h"
+#include "qemu/main-loop.h"
+
+void qemu_mutex_lock_iothread(void)
+{
+}
+
+void qemu_mutex_unlock_iothread(void)
+{
+}