Thrift: Changing TFileTransport to use the same buffer-swap mechanism that pillar...

Thrift: Changing TFileTransport to use the same buffer-swap mechanism that pillar does

Reviewed by: aditya

Tested with thrift test class

Notes: TFileTransport used to use a circular buffer.  Changed this to use two large buffers, one for reading and one for writing, that are swapped whenever the writer thread finishes with the last write.

Also changed a few default constants -- force_flush timeout is now 3 sec, default buffer size is 10000 entries

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@664997 13f79535-47bb-0310-9956-ffa450edef68