Use shlex.split() to parse --special-command test argument

Use shlex.split() to parse --special-command test argument

This allows passing commands with quoted spaces, such as:
  tools/test-wrapper-gypbuild.py --special-command \
    "$DR/bin64/drrun -ops '-reset_every_nth_pending 0' @" \
    ...

R=jkummerow@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=12744

[Reid Kleckner (google), 2012-10-15 17:03:09]

Hello, I work on Dr. Memory and DynamoRIO, and I'm trying to set up a bot to
test DR running V8 on its test suite.  This patch will let me pass through the
DR command prefix without too many shell escaping acrobatics.

---
Background:

DynamoRIO is a dynamic binary instrumentation framework like Valgrind.  Unlike
Valgrind, we use page protections and sandboxing to detect code modification,
while Valgrind relies on annotations in V8.

We keep hitting corner case bugs in DR while running full chrome that come from
V8's code modification.  Debugging these issues in full chrome is really slow
and difficult.  V8's test suite finds the same issues in DR more quickly and is
more reproducible.  So, my goal is to get DR through the V8 test suite and set
up a bot so we don't regress.

Here's the bot I'm working on:
http://build.chromium.org/p/client.dynamorio/builders/linux-v8-dr/
Currently it just builds bleeding-edge V8 and runs some tests.

I'm not a V8 contributor, so let me know if I need to do anything else to get
the patch committed.  Thanks!

[Jakob Kummerow, 2012-10-16 16:19:35]

LGTM. I'll land this for you.

Please note that test.py is about to be replaced by tools/run-tests.py. The
latter is not used on the buildbots yet, but that will most likely change within
the next few weeks. At that point, --special-command will disappear, to be
replaced by --command-prefix and --extra-flags (to specify the stuff before and
after the '@' in --special-command). That should mostly be a drop-in
replacement, but some minor updating of the bot configs might be necessary.