Remove an ill-formed Vca_VcaError from the Vca build.
Remove an ill-formed Vca_VcaError from the Vca build.

VcaError uses a long deprecated model for implementing interfaces.  It is not
used anywhere in this code base and, because it fails to provide some required
virtual overrides, it doesn't compile on the Mac and probably wouldn't work even
it did.  Remove it.

VisionAerie/vision,MichaelJCaruso/vision,VisionAerie/vision,MichaelJCaruso/vision,MichaelJCaruso/vision,MichaelJCaruso/vision,VCommitter/vision,vision-dbms/vision,VCommitter/vision,VCommitter/vision,c-kuhlman/vision,c-kuhlman/vision,vision-dbms/vision,VisionAerie/vision,VisionAerie/vision,c-kuhlman/vision,VCommitter/vision,vision-dbms/vision,VisionAerie/vision,MichaelJCaruso/vision,vision-dbms/vision,VisionAerie/vision,vision-dbms/vision,c-kuhlman/vision,vision-dbms/vision,MichaelJCaruso/vision,c-kuhlman/vision,VCommitter/vision,VCommitter/vision,VisionAerie/vision,VCommitter/vision