* Move tools/bazel.rc to prepare for bazel 0.17
Bazel 0.17 will no longer import the legacy "tools/bazel.rc" config
file. This change ensures compatibility with the new versions.
For users on bazel 0.16 and earlier who have a ~/.bazelrc, this change
will cause bazel to ignore their ~/.bazelrc and load this one instead.
Hopefully this won't break anyone. (famous last words)