[client] add DISALLOW_COPY_AND_ASSIGN() for a few classes

After making the copy constructor and the assignment operator for the
ResourceMetrics class private, I took a quick look at the other exported
classes in the Kudu C++ client API and added corresponding macro
where appropriate.

Strictly speaking, this change breaks the ABI compatibility for the
Kudu C++ client API, but a code that would use these privatized members
was unsafe anyways.  I guess it's easier to fix the linker error after
upgrading to a newer version of the Kudu client library than have
a hidden memory corruption problem in a Kudu C++ application.

Change-Id: I5369760db3040c0357517903dab6ff4e2acb7656
Reviewed-on: http://gerrit.cloudera.org:8080/18511
Tested-by: Kudu Jenkins
Reviewed-by: Riza Suminto <riza.suminto@cloudera.com>
Reviewed-by: Attila Bukor <abukor@apache.org>
2 files changed