Build fix for CUDA backend when using boost 1.60
Build fix for CUDA backend when using boost 1.60

ghisvail/arrayfire,9prady9/arrayfire,9prady9/arrayfire,marbre/arrayfire,bkloppenborg/arrayfire,arrayfire/arrayfire,marbre/arrayfire,munnybearz/arrayfire,shehzan10/arrayfire,umar456/arrayfire,ghisvail/arrayfire,shehzan10/arrayfire,umar456/arrayfire,ghisvail/arrayfire,9prady9/arrayfire,9prady9/arrayfire,merlin-ext/arrayfire,victorv/arrayfire,umar456/arrayfire,arrayfire/arrayfire,munnybearz/arrayfire,umar456/arrayfire,arrayfire/arrayfire,merlin-ext/arrayfire,shehzan10/arrayfire,victorv/arrayfire,victorv/arrayfire,bkloppenborg/arrayfire,bkloppenborg/arrayfire,ghisvail/arrayfire,munnybearz/arrayfire,arrayfire/arrayfire,victorv/arrayfire,shehzan10/arrayfire,marbre/arrayfire,merlin-ext/arrayfire,marbre/arrayfire,merlin-ext/arrayfire,bkloppenborg/arrayfire