The web wizard runs some XSLT over the exported file.  It registers
a handler that is called when the output stream is closed, and this
Process.streamClosedHandler() calls terminate(), which causes the
deadlock, because it wants to join() the extra XSLT thread but the
handler is actually called from the XSLT thread itself.

Fix that by moving the terminate() to another function that runs in the
main thread.

It does not deadlock on Unixes because osl_joinWithThread() actually
detects an attempt to join the calling thread and returns early.

Change-Id: Ia176562fa28b97c7e8956c1e8975c9aa6ee23236