Fix missing "re" module import in GDB support script

Fix missing "re" module import in GDB support script

The gdb-v8-support.py script uses the "re" module to match regular expression,
but it does not import it, resulting in an error when loading the script from
GDB. This patch adds the missing import.

BUG=

Committed: https://crrev.com/abcab811b4a8d67a921aa517be1951ad79f8f99b
Cr-Commit-Position: refs/heads/master@{#29770}

[aperez, 2015-07-20 16:50:41]

aperez@igalia.com changed reviewers:
+ machenbach@chromium.org, machenbach@google.com, wingo@igalia.com

[Michael Achenbach, 2015-07-21 06:59:22]

lgtm

[aperez, 2015-07-21 09:01:08]

The CQ bit was checked by aperez@igalia.com

[commit-bot: I haz the power, 2015-07-21 09:01:19]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1245713002/1

[commit-bot: I haz the power, 2015-07-21 09:28:38]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2015-07-21 09:28:58]

Patchset 1 (id:??) landed as
https://crrev.com/abcab811b4a8d67a921aa517be1951ad79f8f99b
Cr-Commit-Position: refs/heads/master@{#29770}