THRIFT-926. cpp: Add configurable buffer recycling for TNonblockingServer

Add methods to TNonblockingServer to set the maximum size of idle read
and write buffers and the check interval (in calls).  When checked, if
the buffers are larger than the configured maximum, they will be resized
down the to maximum size.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@1005164 13f79535-47bb-0310-9956-ffa450edef68
2 files changed