FindCUDA: Remove duplicate entries from INCLUDE_DIRECTORIES.

As of CMake 2.8.8, the INCLUDE_DIRECTORIES() command does
not de-duplicate entries. Failure to do so can lead to an extremely
long and repetitive list of -I entries on the command line.

Modules/FindCUDA.cmake

@@ -1021,7 +1021,10 @@ macro(CUDA_WRAP_SRCS cuda_target format generated_files)
   # Initialize our list of includes with the user ones followed by the CUDA system ones.
   set(CUDA_NVCC_INCLUDE_ARGS ${CUDA_NVCC_INCLUDE_ARGS_USER} "-I${CUDA_INCLUDE_DIRS}")
   # Get the include directories for this directory and use them for our nvcc command.
+  # Remove duplicate entries which may be present since include_directories
+  # in CMake >= 2.8.8 does not remove them.
   get_directory_property(CUDA_NVCC_INCLUDE_DIRECTORIES INCLUDE_DIRECTORIES)
+  list(REMOVE_DUPLICATES CUDA_NVCC_INCLUDE_DIRECTORIES)
   if(CUDA_NVCC_INCLUDE_DIRECTORIES)
     foreach(dir ${CUDA_NVCC_INCLUDE_DIRECTORIES})
       list(APPEND CUDA_NVCC_INCLUDE_ARGS -I${dir})