Change file names in comments to match the files they are in

Some of these are leftovers from renaming the files, others
are just typos.

Also introduce an ugly awk script to enforce this.

tools/virsh-interface.h

@@ -1,5 +1,5 @@
 /*
- * virsh-interface.c: Commands to manage host interface
+ * virsh-interface.h: Commands to manage host interface
  *
  * Copyright (C) 2005, 2007-2012 Red Hat, Inc.
  *

tools/virsh-network.h

@@ -1,5 +1,5 @@
 /*
- * virsh-network.c: Commands to manage network
+ * virsh-network.h: Commands to manage network
  *
  * Copyright (C) 2005, 2007-2012 Red Hat, Inc.
  *

tools/virt-host-validate.c

@@ -1,5 +1,5 @@
 /*
- * virt-host-check.c: Sanity check a hypervisor host
+ * virt-host-validate.c: Sanity check a hypervisor host
  *
  * Copyright (C) 2012 Red Hat, Inc.
  *