guard OS specific syscalls with file build tags

[Cody Oss]

I was looking at this repo earlier today to look into an issue and notices some files in the tools .integration_tests dir use syscalls that my m1 mac did not like making it so I could not build the project locally. I would recommend guarding such syscalls with build tags -- or document limitations that this project can only work on linux. But since this was just in the testing dir it seems like boarder compatibility could be achieved by using tags.

[Tulsi Shah]

Hi @codyoss, gcsfuse is not supporting mac os, which is mentioned here.

[Ayush Sethi]

Closing in favor of #1078 (comment)