Leaks runner improvements

[gottesmm]

This PR does two different things:

1. It makes leaks runner support C-c.
2. It makes leaks runner fail nicely when a subtask segfaults instead of just throwing an IndexError.

rdar://31544274

[gottesmm]

@swift-ci python lint

[gottesmm]

@swift-ci smoke test and merge

[gottesmm]

@erg @shahmishal

Question. I ran python lint and it succeeded. Why is it also failing when performing smoke tests?

[gottesmm]

*Why is it failing in the smoke tests when python lint succeeded on the bot.

[gottesmm]

@swift-ci smoke test and merge

[gottesmm]

@swift-ci smoke test and merge

[shahmishal]

smoke test has python lint test now:

FAIL: Swift(macosx-x86_64) :: Python/python-lint.swift (8776 of 9637)
******************** TEST 'Swift(macosx-x86_64) :: Python/python-lint.swift' FAILED ********************
Script:
--
/usr/bin/python /Users/buildnode/jenkins/workspace/swift-PR-osx-smoke-test/branch-master/swift/utils/python_lint.py
--
Exit Code: 1

Command Output (stdout):
--
./benchmark/scripts/Benchmark_RuntimeLeaksRunner.in:115:19: E128 continuation line under-indented for visual indent

--

********************

[shahmishal]

*Why is it failing in the smoke tests when python lint succeeded on the bot.

Good question.

[gottesmm]

@shahmishal I know. That is awesome = ). I am just asking why there is a discrepancy in between the two.