bump executor
bump executor

[finishes #101689994]

Submodule src/github.com/cloudfoundry-incubator/executor 1aff0ea..6ed0157:
  > Use WaitForWatcherAndIncrement for golang 1.5.3

Signed-off-by: Jen Spinney <475b118f8db4f150e7ed3b69b35fd7c857f9c9f8@hpe.com>

cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release,cloudfoundry-incubator/diego-release