NaCl: Update revision in DEPS, r13921 -> r13931

NaCl: Update revision in DEPS, r13921 -> r13931

This pulls in the following Native Client changes:

r13922: (shyamsundarr) cleanup special case compatibility with old validator for avx.
r13923: (mcgrathr) Update nacl_arm_newlib toolchain
r13924: (dschuff) PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS
r13925: (shyamsundarr) fix the check_decoder_test.
r13926: (dschuff) Fix build directory for LLVM regression test runner
r13927: (dschuff) Update revision for PNaCl r13918->r13925
r13928: (dyen) Disable flaky IRT extension thread tests on asan mac bots.
r13931: (shyamsundarr) fix lahf feature detection.

BUG=none
TEST=browser_tests and nacl_integration
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_rel_precise32,linux_nacl_sdk,linux_chromium_dbg

Committed: https://crrev.com/14ad520f6a50ca58750fd6e55f9f6d2d4b5b6bf4
Cr-Commit-Position: refs/heads/master@{#300149}

[Mark Seaborn, 2014-10-17 17:32:27]

mseaborn@chromium.org changed reviewers:
+ dschuff@chromium.org

[Derek Schuff, 2014-10-17 17:57:38]

lgtm

[Mark Seaborn, 2014-10-17 18:50:34]

The CQ bit was checked by mseaborn@chromium.org

[commit-bot: I haz the power, 2014-10-17 18:51:22]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/662473004/1

[commit-bot: I haz the power, 2014-10-17 20:02:47]

Committed patchset #1 (id:1)

[commit-bot: I haz the power, 2014-10-17 20:04:15]

Patchset 1 (id:??) landed as
https://crrev.com/14ad520f6a50ca58750fd6e55f9f6d2d4b5b6bf4
Cr-Commit-Position: refs/heads/master@{#300149}