NaCl: Update revision in DEPS, 9cb3a31 -> b2c6249

NaCl: Update revision in DEPS, 9cb3a31 -> b2c6249

This pulls in the following Native Client changes:

e99966a: (mseaborn@chromium.org) Move syscall handler table into NaClApp, instead of it being a global array
0f30d70: (sbc@chromium.org) Remove hardcoded location for mips gcc compiler
20e82d0: (leslieb@chromium.org) Initial x86-32 validator hook implementation for safe remote debugging in nacl.
e91fa6d: (kschimpf@google.com) PNaCl: Update Subzero revision in pnacl/COMPONENT_REVISIONS
cd7b373: (sbc@chromium.org) Disable pnacl_dynloader for mips
ac2c414: (sbc@chromium.org) [MIPS] Add MIPS trusted toolchain to toolchain_revisions
490baeb: (dschuff@chromium.org) PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS
efd02a4: (sbc@chromium.org) Add arm glibc support for gyp build
04818d4: (sbc@chromium.org) Port some changes from chromium's common.gypi
1bd60be: (bradnelson@chromium.org) Disable perf graph upload for android builders.
b2c6249: (jvoung@chromium.org) Update revision for PNaCl

Changes: https://chromium.googlesource.com/native_client/src/native_client/+log/9cb3a31796937176950f1727ea5b7778c9861ae5..b2c6249aa6eea12a4bd6ef09e2cfd6a5bd14ed61

BUG=none
TEST=browser_tests and nacl_integration
CQ_EXTRA_TRYBOTS=tryserver.chromium.linux:linux_chromium_dbg_32_ng,linux_arm_compile,linux_nacl_sdk_build

Review URL: https://codereview.chromium.org/1218233003

Cr-Commit-Position: refs/heads/master@{#337147}