Workaround gcc 4.2's problem with the sequential implementation of general_copy.
Workaround gcc 4.2's problem with the sequential implementation of general_copy.

Fixes #420

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