Add a script to extract VSS SDK headers on POSIX system

Add a script to extract VSS SDK headers on POSIX system

VSS SDK(*) setup.exe is only runnable on Windows. This adds a script
to extract VSS SDK headers on POSIX-systems using msitools.

  * http://www.microsoft.com/en-us/download/details.aspx?id=23490

From: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Tomoki Sekiyama <tomoki.sekiyama@hds.com>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>