deps: Implement fakesyscalls

fakesyscalls is a new library that currently fakes out the 'open' and 'creat'
syscalls. It can be used to redirect the open syscall for a file to another file
specified using the environment variable FILE_REDIRECTIONS_PRELOAD.

BUG=chromium:297876
TEST=Manually test that file redirections work properly.

Change-Id: If5bcb7fd364823b4a0a458719d3e024bd1db540b
Reviewed-on: https://chromium-review.googlesource.com/175212
Reviewed-by: Prathmesh Prabhu <pprabhu@chromium.org>
Commit-Queue: Prathmesh Prabhu <pprabhu@chromium.org>
Tested-by: Prathmesh Prabhu <pprabhu@chromium.org>
4 files changed