Revision 665262

Thrift: Zlib transport.

Summary:
Add a new transport to the C++ library: TZLibTransport.
This wraps another transport (just like TBufferedTransport),
compresses the data written to it, and uncompresses the data it reads.

Reviewed By: mcslee

Test Plan:
For ax_lib_zlib.m4
 - Ran ./bootstrap.sh.
 - Looked at configure.
 - Ran ./configure.
 - Looked at config.status
 - Ran ./configure --with-zlib=/usr.
 - Looked at config.status
 - Changed configure.ac to AC_LIB_ZLIB(1.2.4)
 - Ran ./configure.
 - Watched it fail.

For TZlibTransport
 - test/ZlibTest.cpp
 - Code coverage (hotness) report sent with review.
 - 100% line coverage for all the good stuff.

Revert Plan: ok