I got a piece of code from github:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/tools/spi/spidev_test.c

I'd like to add it somewhere under _tools/testing_ and build it there. 

Not sure if this is appropriate? If so, how do I go about this?

If not, what's the best way to build this?