PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS

PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS

This pulls in the following LLVM changes:

899d5ab: (stichnot@chromium.org) Allow the LLVM cmake build to use ccache.
c5f8056: (jfb@chromium.org) ExpandVarArgs: don't pack the vararg struct

BUG= https://code.google.com/p/nativeclient/issues/detail?id=4102
TEST= PNaCl toolchain trybots
TBR= dschuff@chromium.org

Committed: https://chromium.googlesource.com/native_client/src/native_client/+/84b4c32e4b53a143a8599d26df25a4d5d996c825

[JF, 2015-03-13 21:36:58]

The CQ bit was checked by jfb@chromium.org

[commit-bot: I haz the power, 2015-03-13 21:37:11]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1008693005/1

[commit-bot: I haz the power, 2015-03-14 03:37:48]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2015-03-14 03:37:49]

Try jobs failed on following builders:
  nacl-arm_opt_panda on tryserver.nacl (JOB_TIMED_OUT,
http://build.chromium.org/p/tryserver.nacl/builders/nacl-arm_opt_panda/builds...)
Timed out jobs are not retried to avoid causing additional load on the builders
with large pending queues.

[JF, 2015-03-14 05:36:46]

The CQ bit was checked by jfb@chromium.org

[commit-bot: I haz the power, 2015-03-14 05:36:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1008693005/1

[commit-bot: I haz the power, 2015-03-14 09:23:55]

Committed patchset #1 (id:1) as
https://chromium.googlesource.com/native_client/src/native_client/+/84b4c32e4...

[JF, 2015-03-14 15:17:59]

A revert of this CL (patchset #1 id:1) has been created in
https://codereview.chromium.org/1002423002/ by jfb@chromium.org.

The reason for reverting is: This causes a bunch of failures on the PNaCl
toolchain waterfall, which seem related to reading bad data from the stack.
Reverting..