Removed a space in set_paths.sh

hpvm/set_paths.sh

 #!/bin/bash
 
 # These paths can be modified by the HPVM user
-CUDA_TOOLKIT_PATH=   # Set this to the root of your CUDA Installation
+CUDA_TOOLKIT_PATH=""  # Set this to the root of your CUDA Installation
 if [ -z "$CUDA_TOOLKIT_PATH" ]
 then
     echo "ERROR: SET CUDA_TOOLKIT_PATH to the Root of your CUDA Installation"