Thrift-1379: fix uninitialized enum values in thrift C++ objects

Thrift-1379: fix uninitialized enum values in thrift C++ objects
Client: cpp
Patch: Dave Watson

The thrift-generated code for C++ class objects does not provide any
initialization for enum values, so they wind up containing random/uninitialized
data. This causes problems when clients do not send argument data, as the server
receives random data rather than zero for unpassed args.
Enums should be initialized to zero.

git-svn-id: https://svn.apache.org/repos/asf/thrift/trunk@1179909 13f79535-47bb-0310-9956-ffa450edef68