message: Update lightstep to 0.6.1.
diff: @@ -34,11 +34,8 @@ REPOSITORY_LOCATIONS = dict(
  remote = "https://github.com/opentracing/opentracing-cpp", # v1.2.0
  ),
  com_lightstep_tracer_cpp = dict(
  - # This picks up a commit after v0.6.0 (d4501f84de2d149da2a7a56c545a1c40f214db3f) that fixes
  - # a Clang build issue.
  - # TODO(htuch): Switch back to regular versioned releases at next release.
  - commit = "1c63a24bd7f4e71ccae0d807afd699c3d49307df",
  - remote = "https://github.com/lightstep/lightstep-tracer-cpp", # v0.6.0+
  + commit = "6a198acd328f976984699f7272bbec7c8b220f65",
  + remote = "https://github.com/lightstep/lightstep-tracer-cpp", # v0.6.1
  ),
  lightstep_vendored_googleapis = dict(
  commit = "d6f78d948c53f3b400bb46996eb3084359914f9b",
  