dispatch fast scan only for POD types
dispatch fast scan only for POD types

--HG--
extra : convert_revision : svn%3A83215879-3e5a-4751-8c9d-778f44bb06a5/trunk%40705

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