Migrate tools/bazelrc to .bazelrc

Since [1] Bazel changed the list of resource file locations.
Adapt to that list and move `%workspace%/tools/bazelrc` to
`%workspace%/.bazelrc`.

[1] https://github.com/bazelbuild/bazel/commit/ec83598

Change-Id: I5cee6312a04d19de4c4c94601e1f5f581f9020be
diff --git a/tools/bazel.rc b/.bazelrc
similarity index 100%
rename from tools/bazel.rc
rename to .bazelrc