THRIFT-922. cpp: When reading strings, borrow first

Attempt to get a pointer to the internal transport buffer before copying
onto the heap.  This improves performance TFramedTransport and
TMemoryBuffer, and with TBufferedTransport if the string fits within the
buffer.

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@1005132 13f79535-47bb-0310-9956-ffa450edef68
2 files changed