message: Modify benchmarks to use new execution_mode API
diff: @@ -146,7 +146,7 @@ class MicroBenchmarks(test.Benchmark):
  def _run(self, func, num_iters, execution_mode=None):
  # call func to maybe warm up the GPU
  ctx = context.context()
  - with ctx.execution_mode(execution_mode):
  + with context.execution_mode(execution_mode):
  func()
  if execution_mode == context.ASYNC:
  ctx.async_wait()
  