Simit does not compile with SIMIT_CUDA_ENABLE

[touste]

I managed to build it successfully after the changes described in the attached diff file.
For information, my setup was the following:
Ubuntu 16.04
Cuda 7.5
LLVM 3.7 (I had to built it with the LLVM_ENABLE_RTTI=ON flag)
Cmake 3.5.1

changes.txt

[stephenchouca]

Thanks for raising the issue! I've incorporated your changes into the code base.