Improve reproducibility of test runs.

Improve reproducibility of test runs.

Add random seed to run-tests.py, using either a user supplied
value or a random number generated by random.SystemRandom().
This same random seed is passed to all test cases, making sure
that we can easily reproduce test failures that depend on
random numbers (i.e. bugs related to our handwritten ASLR).

Also fix all uses of rand() to make use of our RNG class
instead.

R=machenbach@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=20637

[Benedikt Meurer, 2014-04-09 18:13:38]

PTAL

[Michael Achenbach, 2014-04-10 07:18:06]

lgtm

[Michael Achenbach, 2014-04-10 07:18:14]

https://codereview.chromium.org/231443002/diff/1/tools/run-tests.py
File tools/run-tests.py (right):

https://codereview.chromium.org/231443002/diff/1/tools/run-tests.py#newcode257
tools/run-tests.py:257: options.random_seed =
random.SystemRandom().randint(-2147483647, 2147483647)
-...48?

[Benedikt Meurer, 2014-04-10 07:25:36]

https://codereview.chromium.org/231443002/diff/1/tools/run-tests.py
File tools/run-tests.py (right):

https://codereview.chromium.org/231443002/diff/1/tools/run-tests.py#newcode257
tools/run-tests.py:257: options.random_seed =
random.SystemRandom().randint(-2147483647, 2147483647)
On 2014/04/10 07:18:14, Michael Achenbach wrote:
> -...48?

Done.

[Benedikt Meurer, 2014-04-10 07:26:04]

Committed patchset #2 manually as r20637 (presubmit successful).