[Bazel] Add empty BUILD file to prevent full build
[Bazel] Add empty BUILD file to prevent full build

Problem
-------
SQ query walks up to find the affected targets,
and end up causing full build for various targets.

Solution
--------
This adds guard `BUILD.bazel` file for all toplevel
directories that do not have a BUILD file.

JIRA Issues: DPB-15983, DPB-14048

Differential Revision: https://phabricator.twitter.biz/D902602

twitter/util,twitter/util,twitter/util