Followup to r1464679: forcibly break some code which is #define'd away, but
won't compile if uncommented.

* tools/client-side/svn-bench/client_errors.h,
* subversion/svn/client_errors.h:
    Break the unused SVN_ERROR_BUILD_ARRAY mode by adding an #error directive.


git-svn-id: https://svn.apache.org/repos/asf/subversion/trunk@1464711 13f79535-47bb-0310-9956-ffa450edef68