Updated the estimate_join_output_size function to return a gdf_error and pass in the size estimate via pointer.
Updated the estimate_join_output_size function to return a gdf_error and pass in the size estimate via pointer.

gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf,gpuopenanalytics/libgdf