NaCl: Update revision in DEPS, r12488 -> r12497

This pulls in the following Native Client changes:

r12489: (jfb) Build libc++/libc++abi with HAS_THREAD_LOCAL
r12490: (jvoung) PNaCl: Update LLVM test suite revision in pnacl/COMPONENT_REVISIONS
r12491: (jvoung) Add dashy repos (llvm-test-suite) to pnacl/deps_update.py
r12492: (mseaborn) Add tests for C++ exception types that use virtual base classes
r12493: (jfb) Update TOOL_REVISIONS for PNaCl 12483->12489
r12494: (mseaborn) PNaCl: Update libcxxabi revision in pnacl/COMPONENT_REVISIONS: SJLJ EH support
r12495: (jfb) Mark faultqueue test as broken on ARM.
r12496: (kschimpf) PNaCl: Update LLVM revision in pnacl/COMPONENT_REVISIONS
r12497: (mseaborn) Update PNaCl toolchain revision to r12494 to get SJLJ EH support for libc++

This pulls in libc++ as the default standard C++ library for PNaCl and allows SJLJ EH to work with libc++.

This also fixes out-of-bounds std::map access in nacl_io testing, and correspondingly broken test. All used  pass because libstdc++ just happened to return the expected value when out-of-bounds, but libc++ doesn't return the same thing and the tests now appeared broken.

BUG=none
TEST=nacl_integration
R=binji@chromium.org, dschuff@chromium.org, ronghuawu@chromium.org

Review URL: https://codereview.chromium.org/98713004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@239294 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 239294