Build a skeleton interceptor for CuFile

[lukemartinlogan]

API interception is the idea that you can change the implementation of a function without having to recompile the code. Hermes, for example, intercepts file I/O APIs (e.g., POSIX) to give applications tiering without having to rebuild them. Linux accomplishes this with the LD_PRELOAD environment variable.

./my_program  # No hermes
LD_PRELOAD=/path/to/libhermes.so ./my_program # With hermes

In this project, we want to intercept cufile instead of POSIX. We have a few files:
cufile_api.h - The interceptor header file (modify this file)
cufile_api.cc - The interceptor implementation (modify this file)
real_api.h - A helper file used in cufile_api.h for loading symbols dynamically from the libraries specified using LD_PRELOAD. (no need to modify this file)

You only need to modify the cufile_api.h and cufile.cc files.