Workaround parallel build race condition on Windows.
Workaround parallel build race condition on Windows.

Fixes #273

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