Make SmallLocksTest pass under TSAN if halt_on_error=0.
Make SmallLocksTest pass under TSAN if halt_on_error=0.

Summary: When setting halt_on_error to 0 (which is the default setting now for TSAN in fbcode because we want to catch all bugs), a deadlock does not immediately cause an issue. So we include exit(0) as part of the death test to handle that case.

Reviewed By: yfeldblum

Differential Revision: D23493015

fbshipit-source-id: fb4910edddab11e1cd00e402b6b7350a6dc941a7

facebook/folly,facebook/folly,facebook/folly,facebook/folly,facebook/folly