PNaCl: Update LLVM revision in pnacl/DEPS
PNaCl: Update LLVM revision in pnacl/DEPS

This pulls in the following LLVM changes:

dad71e1: (jfb@chromium.org) Properly support 16-bit atomics on x86-32.

BUG= https://code.google.com/p/nativeclient/issues/detail?id=3579
BUG= https://code.google.com/p/nativeclient/issues/detail?id=2981
BUG= https://code.google.com/p/nativeclient/issues/detail?id=3475
TEST=PNaCl toolchain trybots
R= dschuff@chromium.org

Review URL: https://codereview.chromium.org/22666006

git-svn-id: 721b910a23eff8a86f00c8fd261a7587cddf18f8@11983 fcba33aa-ac0c-11dd-b9e7-8d5594d729c2

Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client,Lind-Project/native_client