Make fill_functor's member be non-const so a copy constructor can be generated.
Make fill_functor's member be non-const so a copy constructor can be generated.

arnabgho/thrust,egaburov/thrust,sarvex/thrust,thrust/thrust,xiongzhanblake/thrust,zeryx/thrust,GrimDerp/thrust,zeryx/thrust,Ricardo666666/thrust,jaredhoberock/thrust,raygit/thrust,xiongzhanblake/thrust,sdalton1/thrust,sarvex/thrust,marksantos/thrust,thvasilo/thrust,mohamed-ali/thrust,andrewcorrigan/thrust-multi-permutation-iterator,sarvex/thrust,thrust/thrust,Ricardo666666/thrust,thrust/thrust,jaredhoberock/thrust,thrust/thrust,jaredhoberock/thrust,dachziegel/thrust,jaredhoberock/thrust,Ricardo666666/thrust,egaburov/thrust,raygit/thrust,arnabgho/thrust,dachziegel/thrust,zhenglaizhang/thrust,andrewcorrigan/thrust-multi-permutation-iterator,marksantos/thrust,thvasilo/thrust,thvasilo/thrust,xiongzhanblake/thrust_src,marksantos/thrust,arnabgho/thrust,egaburov/thrust,xiongzhanblake/thrust,zeryx/thrust,zhenglaizhang/thrust,raygit/thrust,jaredhoberock/thrust,sdalton1/thrust,mohamed-ali/thrust,GrimDerp/thrust,xiongzhanblake/thrust_src,andrewcorrigan/thrust-multi-permutation-iterator,mohamed-ali/thrust,zhenglaizhang/thrust,thrust/thrust,GrimDerp/thrust,xiongzhanblake/thrust_src,dachziegel/thrust,sdalton1/thrust