Migrate `tools/bazel.rc` 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: Ifff9de1e4940909512f3109051bffe39b3621aa3

.bazelrc

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