Add support for writing to compressed file streams from clients

_From [hazelw...@google.com](https://code.google.com/u/110363031187200803796/) on June 01, 2012 18:33:44_

Many end users are doing program instrumentation that results in extremely large output files, especially for large realistic guest applications. It would be ideal to allow users to write directly to compressed output files.

The zlib library contains gzopen, gzprintf, and gzclose to make this seamless.

Doing this safely might come with some interesting challenges.

_Original issue: http://code.google.com/p/dynamorio/issues/detail?id=790_