Migrate (i.e. move) `tools/bazel.rc` to `.bazelrc`

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

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

Change-Id: I91a52b2aaa1d9a58f5865c7590c3af47cc5f115f
diff --git a/tools/bazel.rc b/.bazelrc
similarity index 100%
rename from tools/bazel.rc
rename to .bazelrc