message: Enable 64 bit integer tests
diff: # git update-index --assume-unchanged tensorflow/compiler/tests/plugin.bzl
  plugins = {
  - "poplar": {"device":"XLA_IPU", "types":"DT_FLOAT,DT_INT32", "tags":[]},
  + "poplar": {"device":"XLA_IPU", "types":"DT_FLOAT,DT_INT32,DT_INT64", "tags":[]},
  "executor": {"device":"XLA_EXEC", "types":"DT_FLOAT,DT_INT32", "tags":[]},
  }
  