Delete the gdig tool.

This was a tool to use the DNS stub resolver from the command line.

The tool has been broken for at least 10 months, since it didn't set
up a task scheduler, but used code that required one. Since no one
noticed for so long, I assume we can just remove it, and have less
code to maintain.

Bug: 865745
Change-Id: Ia3c9e7ec5a038acaf1d1318a8aeab79192c526ae
Reviewed-on: https://chromium-review.googlesource.com/1145714
Reviewed-by: Misha Efimov <mef@chromium.org>
Reviewed-by: John Budorick <jbudorick@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#577051}
5 files changed