ROCHESTER — IBM is investing at least $5 million to expand a northwest Rochester building to consolidate its specialized electronics testing lab into one complex, which is not located on its former campus. Construction is underway to add 8,736 square feet of space to the 14,232-square-foot industrial building at 3222 40th Ave. NW. IBM leases the property from CDP Partners LLC of Rochester. Signage labels the property as " IBM - Building 684." Bu…