client: If boost::thread_interrupted was thrown while a request was executed,...

client: If boost::thread_interrupted was thrown while a request was executed, block until the request was processed by the RPC client to avoid use-after-delete situations.

git-svn-id: https://xtreemfs.googlecode.com/svn/trunk@3028 f8528748-c2c0-11dd-ba5c-d3b7c2b3b534