Add set_union performance test
Add set_union performance test

UIKit0/thrust,google-code-export/thrust,malenie/thrust,lishi0927/thrust,julianromera/thrust,UIKit0/thrust,google-code-export/thrust,malenie/thrust,bfurtaw/thrust,google-code-export/thrust,rdmenezes/thrust,UIKit0/thrust,lishi0927/thrust,rdmenezes/thrust,allendaicool/thrust,malenie/thrust,levendlee/thrust,levendlee/thrust,hemmingway/thrust,h1arshad/thrust,levendlee/thrust,bfurtaw/thrust,Vishwa07/thrust,Vishwa07/thrust,google-code-export/thrust,levendlee/thrust,julianromera/thrust,h1arshad/thrust,UIKit0/thrust,lishi0927/thrust,Vishwa07/thrust,allendaicool/thrust,lishi0927/thrust,bfurtaw/thrust,allendaicool/thrust,hemmingway/thrust,julianromera/thrust,h1arshad/thrust,h1arshad/thrust,malenie/thrust,allendaicool/thrust,hemmingway/thrust,rdmenezes/thrust,rdmenezes/thrust,Vishwa07/thrust,julianromera/thrust,bfurtaw/thrust,hemmingway/thrust