Bendroid: Add a sentinel test and benchmark so we don't lose the last bit of output when the program exits.
Bendroid: Add a sentinel test and benchmark so we don't lose
the last bit of output when the program exits.

Change-Id: I7c9be95080b8ea9ce89eb7f5b89bef5d3b6a1e00

vanadium/go.devtools,vanadium/go.devtools,vanadium/go.devtools