re-enabled optimized fill() using a different technique than before
re-enabled optimized fill() using a different technique than before

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