qemu: Fix qemuMonitorOpen prototype

Commit id '85af0b80' added a 'timeout' as the 4th parameter to
qemuMonitorOpen, but neglected to update the ATTRIBUTE_NONNULL(4)
to be (5) for the cb parameter.

src/qemu/qemu_monitor.h

@@ -249,7 +249,7 @@ qemuMonitorPtr qemuMonitorOpen(virDomainObjPtr vm,
                                unsigned long long timeout,
                                qemuMonitorCallbacksPtr cb,
                                void *opaque)
-    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(4);
+    ATTRIBUTE_NONNULL(1) ATTRIBUTE_NONNULL(2) ATTRIBUTE_NONNULL(5);
 qemuMonitorPtr qemuMonitorOpenFD(virDomainObjPtr vm,
                                  int sockfd,
                                  bool json,